I decided to sign up for testing the “Brush Tips”. (*5)
Preparation:
Downloaded requested Brush Tip file “3 cartoon eye by cr.abr” and checked its content with abrMate (*1). Included are the three Brush Tips:
- 3 cartoon eye by cr_1
- 3 cartoon eye by cr_2
- 3 cartoon eye by cr_3
Test performed on a PC with Windows 10 Pro and krita-nightly-x64-5.0.0-beta1-7f1fe37732 in a separate user account, always tested on my default canvas template, deleted “resourcecache.sqlite” from the resource folder after each test.
Information from Krita >> Help >> Report Bug
Krita
Version: 5.0.0-beta1 (git 7f1fe37)
Languages: en_US, en, en_US, en, en_US, en, en_US, en, en_US, en, en_US, en, en_US, en, en_US, en, de_DE, de, en_US, en
Hidpi: true
Qt
Version (compiled): 5.12.11
Version (loaded): 5.12.11
OS Information
Build ABI: x86_64-little_endian-llp64
Build CPU: x86_64
CPU: x86_64
Kernel Type: winnt
Kernel Version: 10.0.18363
Pretty Productname: Windows 10 (10.0)
Product Type: windows
Product Version: 10
OpenGL Info
Vendor: “ATI Technologies Inc.”
Renderer: “Radeon RX 580 Series”
Version: “3.0.13596 Compatibility Profile Context 20.10.35.02 27.20.1034.6”
Shading language: “4.60”
Requested format: QSurfaceFormat(version 3.0, options QFlagsQSurfaceFormat::FormatOption(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8, samples -1, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 0, colorSpace QSurfaceFormat::DefaultColorSpace, profile QSurfaceFormat::CompatibilityProfile)
Current format: QSurfaceFormat(version 3.0, options QFlagsQSurfaceFormat::FormatOption(DeprecatedFunctions), depthBufferSize 24, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 8, samples 0, swapBehavior QSurfaceFormat::DoubleBuffer, swapInterval 1, colorSpace QSurfaceFormat::sRGBColorSpace, profile QSurfaceFormat::NoProfile)
Version: 3.0
Supports deprecated functions true
is OpenGL ES: false
QPA OpenGL Detection Info
supportsDesktopGL: true
supportsAngleD3D11: true
isQtPreferAngle: true
Hardware Information
GPU Acceleration: desktop
Memory: 98227 Mb
Number of Cores: 24
Swap Location: D:/_TEMP
Current Settings
Current Swap Location: D:/_TEMP
Current Swap Location writable: true
Undo Enabled: true
Undo Stack Limit: 200
Use OpenGL: true
Use OpenGL Texture Buffer: true
Disable Vector Optimizations: false
Disable AVX Optimizations: false
Canvas State: OPENGL_SUCCESS
Autosave Interval: 900
Use Backup Files: true
Number of Backups Kept: 1
Backup File Suffix: ~
Backup Location: Same Folder as the File
Backup Location writable: false
Use Win8 Pointer Input: false
Use RightMiddleTabletButton Workaround: false
Levels of Detail Enabled: false
Use Zip64: false
Display Information
Number of screens: 2
Screen: 0
Name: \.\DISPLAY1
Depth: 32
Scale: 1
Resolution in pixels: 1920x1080
Manufacturer:
Model:
Refresh Rate: 60
Screen: 1
Name: \.\DISPLAY2
Depth: 32
Scale: 1
Resolution in pixels: 1920x1080
Manufacturer:
Model:
Refresh Rate: 50
Current Settings
Current Swap Location: D:/_TEMP
Current Swap Location writable: true
Undo Enabled: true
Undo Stack Limit: 200
Use OpenGL: true
Use OpenGL Texture Buffer: true
Disable Vector Optimizations: false
Disable AVX Optimizations: false
Canvas State: OPENGL_SUCCESS
Autosave Interval: 900
Use Backup Files: true
Number of Backups Kept: 1
Backup File Suffix: ~
Backup Location: Same Folder as the File
Backup Location writable: false
Use Win8 Pointer Input: false
Use RightMiddleTabletButton Workaround: false
Levels of Detail Enabled: false
Use Zip64: false
Current Settings
Current Swap Location: D:/_TEMP
Current Swap Location writable: true
Undo Enabled: true
Undo Stack Limit: 200
Use OpenGL: true
Use OpenGL Texture Buffer: true
Disable Vector Optimizations: false
Disable AVX Optimizations: false
Canvas State: OPENGL_SUCCESS
Autosave Interval: 900
Use Backup Files: true
Number of Backups Kept: 1
Backup File Suffix: ~
Backup Location: Same Folder as the File
Backup Location writable: false
Use Win8 Pointer Input: false
Use RightMiddleTabletButton Workaround: false
Levels of Detail Enabled: false
Use Zip64: false
1st test:
Import in Brush Editor (Import in brush editor, then select as a brush tip for the current preset):
Import the file “3 cartoon eye by cr.abr” via:
a. Settings >> Manage Resources Libraries… >> Import
b. Settings >> Manage Resources… >> Import Resources
c. the button Import in the Brush Editor
(d. use a filemanager to copy it in this folder before starting Krita)
I repeated the following for a, b and c 5 times each, the result was always identical:
After the import in the Brush Editor window only the Brush Tips “3 cartoon eye by cr_2” and “3 cartoon eye by cr_3” are displayed, Brush Tip “3 cartoon eye by cr_1” was missing at all attempts. (*2) 
The two imported Brush Tips could be selected and you can use them on the scratchpad as well as on the canvas. 
#######
2nd test:
Brush tips chooser (Loading brush tips from inside a folder inside /brushes/):
For this I copied 3 folders with different brush tips into the folder Brushes,
contained brush tips of the formats: *.abr, *.gbr, *.gih, *.png, *.svg, *.vbr
Except for *.vbr-Brush (
Tiar: I don’t think vbr is supported by Krita) Tips all other formats are recognized in subfolders and they are usable on Scratchpad and Canvas, apart from the error concerning ABR files described in test 1 and 3 this is also true for these files (you can not use their first Brush Tip ).
I have not been able to get the *.vbr-Brush Tips to show up in Krita either inside subfolders, or directly from the “brushes” directory. I also tried to import them via the resource manager and from the brush editor, but always unsuccessfully, VBR-BRUSH TIPS CANNOT BE IMPORTED (at least they are not displayed).
I have successfully repeated the test with the working Brush Tips 5 times each. With the *.vbr-Brush Tips I gave up after about 10 attempts. (However, I don’t know of any *.vbr brush tips other than the “Chaos&Evolutions brushes”, from 2010, by David Revoy (@deevad) and therefore consider it unsightly but not as catastrophe ATM.) (*3)
#######
3. test:
Brush Tips chooser (Import a .abr library):
In addition to the given ABR file “3 cartoon eye by cr.abr” used in the first test, I tested three ABR files by “Andrei Oprinca” (*4) from my personal use stock, “Flying-Birds-Brushes” with ~200 kB and 11 Brush Tips, “Premium-Animal-Brushes” with ~2 MB and 122 Brush Tips and “Tree-Brushes” with ~56 MB and 51 Brush Tips, to check this I viewed the files in abrMate.
Again, for all three files, the first Brush Tip is not displayed, as in Test 1 with “3 cartoon eye by cr.abr”. But the displayed Brush Tips can also be selected for these 3 files and are displayed correctly in the scratchpad and on the canvas.
I repeated this test 5 times with identical results.
#######
additional tests:
4th test:
Using the “Stamp” function in the Brush Editor on the canvas, import selected areas as Brush Tip.
For this I selected different areas of the canvas switched to the Brush Editor and imported and saved the respective selection as Brush Tip and successfully tested the generated Brush Tip in the scratchpad and on the canvas, I tested this 3 times with different sized selections and finally once without selection imported the entire canvas as Brush Tip and also tested that successfully in the scratchpad and on the canvas.
#######
5th test:
Using the Clipboard function to import clipboard content as a Brush Tip.
I imported and saved three images copied to the clipboard as Brush Tip by pressing the “Clipboard” button in the Brush Editor, all three Brush Tips could be used normally on canvas and scratchpad, I repeated this 3 times,
this did not work with texts in the clipboard 
___ (Tiar: I think that’s kind of expected maybe someone could convert it to the Text Brush Tip… but that’s kinda useless).
#######
Main finding, the first brush tip of ABR files is not displayed and VBR files seemed to be accepted for import but they are not displayed. 
Everything else tested worked. 
(And now I’m working on the bug reports. )
I hope the test was up to the mark (Tiar: yes 
). If I have forgotten something or have to rework, please contact me.
Michelist
Footnotes:
(*1) This software can read and display most of the currently available ABR files, except for specially copy-protected ones, and is able to convert newer ABR files created with Photoshop CS versions into Photoshop 7 format to use them in non-CS format compatible software (most software can work with this format, including Krita). You can also use abrMate to extract the Brush Tips as PNG files with transparency, so it is possible to assign the first Brush Tip to a preset, should you need it.
The homepage is -at the moment- still available, but seems to be no longer maintained, all download links there don’t work anymore, however abrMate can be downloaded from Archive(dot)org, this is the direct download link from Archive(dot)org, but it can be very slow in rare cases, or has to be restarted.
(*2) & (*3) Actually I have not been able to find a previous bug report for either bug and am opening two new bug reports for bugs.kde.org, which perhaps may take a while due to the fact that these are my first bug reports and my health, but I’ve already started writing them.
(*4) Links to the used resources:
Flying birds brushes by Andrei-Oprinca on DeviantArt
https://resources.psdbox.com/downloads/animal-brushes-pack
Tree Brushes Pack - Resources Box
Chaos&Evolutions brushes - David Revoy
& the requested file:
3 Set of Eyes For Character Doodles Brushes - Free Photoshop Brushes at Brusheezy!
(*5) TL,DR
I deliberately did not agree to take this test beforehand because my health has been giving me very serious problems for a few weeks and I did not know if I could do it at all, as I have a severe illness flare-up.
Fortunately I was able to continue working here whenever the body allowed it, unlike the normal forum operation, which I can hardly follow at the moment because I often fall asleep uncontrollably and sleep up to 20 hours on some days. Whereby this is a kind of up and down. As soon as I recover, I hopefully will be active in the forum more often again. Not as sporadically as at the moment.
#######
EDIT / ADD: The first bug with the ABR files is filed / created and can be found here: 442474 – The first brush tip of ABR-Files isn't loaded