X to Rotate Crop

It’s an unusual problem that does not happen on my Mac either. But we can try to interpret some clues.

The X shortcut should not normally make that alert appear (“Remove Photo…”). The keyboard action that normally makes that appear on a Mac is pressing the Delete key when a folder is the selected source.

We’ll assume that the Delete key is not actually being pressed, because you’re pressing the X key. That leads to the question, what would cause a Mac to think that an X key means the Delete key? One angle would be to look at any software that might be installed that remaps keys or launches macros with a keyboard shortcut. Another thing to look at is which language that macOS is set to, because X is the shortcut on a US English keyboard and might differ for other languages.

Also make sure you have tried restarting Lightroom Classic and tried restarting the Mac, in case it was just some weird temporary problem.

If the problem persists, a workaround is that if you only want to undo a crop rotation you just did, instead of pressing X again to forward rotate (which adds a second crop rotation step in the History panel, for a total rotation of 180 degrees), press the Undo keyboard shortcut instead (backs out of the crop rotation History step for a total rotation back to the original 0 degrees).