I was working on a project in the VSE and editing some keyframes via the graph editor. I believe I used key: Mirror as my last known command because I was trying to invert the keyframe positions. It didn't work, the keyframe became a solid line and moved downwards for some reason, I went to undo and undo didn't work.
I've spent another 30 minutes in the project thinking it would fix itself, it didn't. I restarted the project still not working.
Looked online, tried shift+alt and shift+w but there was no change or any indication that keyboard change was the cause. I'm using qwerty and it's supposed to be control+z to undo and control+shift+z to redo as its always been. Checking controls it indeed still is. Under undo steps they had been set to 42 a while back and global was always on. I moved them to a lower value, no change. Keyboard is set to the same language its always been in the windows tray. I'm at a loss here on what happened or how to fix it. Only remaining thing I can think of is to mess around with the graph editor and see if that jogs it, perhaps a bug with the mirror options, perhaps it was an earlier operation or a bad strip in the vse?
This is rather upsetting as I still have a fair amount of work left to do on the project, mainly the finishing touches and filters and special effects, and those are the ones you need undo the most for.