Krita 2.3.0 & Digikam 7.0.0-rc / Thumbnail


With Digikam (7.0.0-rc), I have some files created with Krita (4.2.9 & 4.3.0), where I don’t see the thumbnail and image too (Failed to load image). I have (38) Krita files, (34) where I can see the thumbnail and image, and (4) where I have the problem.
After few tests, the problem comes from Krita 2.3.0, because when saving the (4) files with Krita 2.2.9, I see the thumbnails and images on Digikam 7.0.0-rc.

Where can I report the bug?

Thank you and best regards,