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Ctrl+A, Ctrl+H and such suddenly stop working

My Studio 2019 after SP1 (go figure…) tends to deactivate basic shortcuts such as ctrl+a, ctrl+z or ctrl+h mid-project, without any obvious reason. It just happens like that. I haven't spotted a pattern so far. Resetting Studio does help, albeit it's NOT a solution, obviously.

Any ideas, other than reinstalling Studio, buying a new PC or committing a suicide and hoping for being born in a world with more install-worthy SPs?