My M1 was removed from "Attack Only Click" and I can't reassign it.

It works everywhere else it's bound to. I can buy items, click on the map, etc. But today, when playing my first game I noticed pretty quickly my M1 wasn't showing my clicks on the screen as I attempted to auto minions with it, only Attack Move Click would work. Went into key bindings and found it no longer bound to that function. I also can't rebind for whatever reason. It exits out of the key assigning when I click but doesn't show M1 added.