Got the same problem. Severals times in a rows, now I am ban form playing again only for that reason, great!
Fourth time i cannot play because of this bug in 2 days, really frustrating.
(I think i lost some LP but i am not sure about it)
Hope it can be fix soon, it's really bothering me.
playing on mac client.
version : League of Legends 6.11.16_05_26_22_56
Precision:
while in champ select,
A count down will go to zero (ban or pick) for a player.
and my client doesn't sync and does not see the choice, everything stay froze.
apparently time goes by and it should be my turn to pick or ban but since client stay on the other player count down at zero I don't have information it is mt turn and no possibility to select.
I notice my team living the chat room and i have to wait several minute to return to the role selection screen.
At this point i can't play cause a apparently have dodge the previous game.