When starting a game, the launcher doesn't appear!

This happened twice on me as I am using MacBook Pro, when I find a match I can chose summoner and everything but when the game starts the launcher doesn't appear which doesn't make me play considering my teammates thinks that I am AFK, so for this reason I am currently banned I guess as my launcher doesn't open because I have reinstalled it to see if anything happens, and I have searched and I didn't find anything.