Switching tools too quickly breaks cached image.

[Ralek]

I use a hotkey to switch between eraser and pen tool, sometimes if I switch and draw too fast, the eraser acts like the pen tool, but looks like the eraser is working. Only when I draw over top of what I "erased" does it reveal the actual image.

How to replicate:
Use 2 hotkeys to switch between a pen tool and a separate eraser tool
eventually you'll find that one of the time you 'erased" actually drew but it didn't show up.

[support]

try to disable GPU for small brushes: Menu-file-options-OpenGL