In sampler mode hotkeys such as Undo/Redo (Ctrl (+ Shift) + Z) or fade in/out (Ctrl + Shift + I / O) doesn’t work anymore… But hotkeys in main mode (Space, Tab and others) still work fine. Why some hotkeys are broken and how to repair?
most hotkeys are tied to which part of the gui has focus. make sure the part you are trying to edit has focus, either by left or middle mouse click, or by cycling through with option+tab (on macOS - not sure on win or linux) or option+shift+tab
Save the file outside windows folder which need administration rights. I save the keymappings file on a separate HDD, on D: , because I have had my kaymappings erased many a times (by Win10?).