[CLIENT] Team Builder - Stuck in Ready when summoner joined and left quickly

This is a timing bug or race condition related to a summoner joining and leaving a team quickly and me hitting ready in between, it would seem. Issue occurred once, entered next game with no issue.

About 8:26pm Eastern, NA Server, ecksate Normal Team Builder 4 players in the team 5th joins, I hit ready immediately He left, and my champ was still hightlighted as if ready, as seen in the screen shot.
They couldn't start the game and we were unable to resolve the problem, they tried toggling their Ready status and they had to kick me Another summoner said that he say thresh as ready but thresh had no problem

Let me know if you have any questions, thanks.