Recently i’ve been finding that cells in my notebooks occasionally stop funtioning properly in the UI (the code is not affected). The main issue is that actionls like “ctrl+Z” and tab indent stop working (tab reverts to showing popup rather than auto-indenting). The cell still runs, and if I delete the cell and move the code to a new cell it all works.
The main bug is that if you select all, Ctrl+X the contents and then make a mistake (i.e. copy something else rather than pasting, you lose work as you can’t “undo” the cut from the affected cell.