Auto-attack Function Non-Functional?

I recently played a 3v3 Co-Op versus AI match for a quick first win. While playing, I noticed my champion, Warwick, wouldn't auto-attack on his own while being attacked by jungle creeps. I checked my settings just to make sure the auto-attack function was still turned on, and it was. It makes it a little more exhausting and frustrating having to click on each individual creep to attack it instead of just going from one to the next. Is anybody else having this issue or does anyone know how to fix it?