In pick and ban phase, I chose my champion but couldn't lock in. Changed champion back and forward and still couldn't lock in. Time ran out, but I was still stuck in the chose your champion thing with 0 seconds left, stuck there. Chat said everyone left the lobby too like a normal dodge would. I had to restart the client or I would be stuck there.
By the way when I say I couldn't lock in I don't mean that I would get that typical error message a lot of people get, no, the button was greyed out and unclickable, like if I didn't chose a champion at all.
If it helps, I chose a champion before the ban phase so that my team would know what it was and a kind player was nice enough to first pick it for me, I don't know if that helped the client bug or not but hey, that was the situation.