Hello, I have this incredibly weird problem on an old iMac. The customer doesn't remember, but it must be at least 9 years old.
Anyway, this is what happens: when I get to the login page, any mouse doesn't left click. Not the official mouse, not a mouse with cord, none of them. The pointer moves but I can't left click anywhere.
So I made a backup and tried reinstalling MacOS: well, mouses won't left click during the install procedure either. The keyboard works, but no mouse will left click.
I sincerely don't know what may be the problem here, so I decided to ask here and see if anyone had a similar problem.