When using Krita with OpenGL ticked under the display tab, the effect the use of any tool creates isn't visible for many seconds. Cursor is also invisible/ appears stuck wherever it was on the canvas area (but the cursor can still be moved to outside the canvas area into menus/dockers etc to use them).
Yes, we know. It's a bug in some Intel display driver versions on Windows. It's FAQ number one, but we still haven't got a system that can reproduce the problem... https://docs.krita.org/KritaFAQ#Krita_starts_with_a_black_or_blank_canvas_and_nothing_changes_when_you_try_to_draw.2Fshows_a_black_or_blank_screen_on_my_Windows_system_with_an_Intel_GPU And nobody is telling us which exact brand and model of system they have, with the exact version of Windows, the display chip and display driver, and whether the system was updated from Windows 7 to Windows 10, or whether it's a clean installation... *** This bug has been marked as a duplicate of bug 360601 ***