Alt Selfcast not working

So I was playing karma when noticed this bug. When I play Karma I always Alt+E to self cast my shield. Same with Orianna's shield and Lissandra's Ult. For some reason it stopped working. I'm not sure why but it's only like that with my Left Alt key. It works when I use my Right Alt key. My Left Alt key isn't broken either. I can alt+tab and do other functions with the alt key. Is there is a specific reason why this is happening? Thanks for any help!