The "Alt" button is tied to a lot of combinations, and now it is not pressed the first time, you have to press twice to make the function complete. For example "Alt" + "Arrow" = Duplication with dragging by 1 pixel (right, left or down and up).
For understanding, check the functions before and after the update. You can say that we were deprived of the "Alt").
The "Alt" itself activates the menu selection, it's understandable. But earlier, in combination with the keys "Alt" performed a command of a combination of keys, but now it does not. Please return this moment, as it was before the October update. Thank you, if someone hears. Believe me, this is important.
A new update to Photoshop was released yesterday, which fixes the Alt key problems.