Ctrl+z (undo) stopped working.

Hi friends,

I'm a big Lightroom Classic user. I was fooling around trying presets and undoing it to see a "kinda" before/after action like I always do. Suddently, Ctrl+z stopped working and Edit - Undo turned pale so cannot be click. I cannot undo anything. Strangely enough, if I tap Ctrl+z fast (fraction of a second) after I did a preset or a setting change, it works.

I tried: Installing older version, re-installing new version, opening another catalog and coming back to my current one, shut down lightroom and the computer.

Ctrl+Z works everywhere else on my computer (photoshop, word, etc).It seems like my Lightroom doesn't record my history anymore. Any of you had the same problem?

Many Thanks!

Mike