My onion skin randomly disappeared when I opened Krita.
The lightbulb is on and I know how to use it. It was working fine
and then one day it wasn’t.
I’m completely stuck. I haven’t done anything differently to when I was using it just fine, but nothing else appears to be wrong so I don’t know if it’s a bug.
Which version (number) of krita are you using and which operating system?
In the Onion Skins docker, are onion skins showing as being on for the onion skins that you expect to be on?
Can you post a full screen screeenshot with Timeline, Layers and Onion Skins docker showing for this situation?
I’m using krita version 3 on a macbook pro with mojave.
I don’t really know what you mean by that but the onion skins should be on.
Actually no and this is why full screen screenshots are often essential.
You have all onion skins turned off:

The number ‘0’ onion skin control column is the overding master control for onion skins for offness and onness and overall opacity.
Here is what happens if you enable the above arrangement by clciking on the number ‘0’:
Please try that.