Alt doesn't work on After Effects 2020

Whenever I'm trying to use roto brush, and after trying to erase some selected parts it simply doesn't work. My paint cursor starts to go from green to gray on repeat. 
Same goes when I'm trying to open expressions on some presented (Im supposed to hold alt and click), nothing happens. I have tried to change languages, reset my preferences, also my keyboard doesn't have any special characters. No idea what I can do.