Can't join a game - "Players not ready" ?

I've played a couple ranked TFT games already this morning, but now it won't let me join a new one. It acts as though I've queued, but doesn't display the queue timer, and says "Players not ready" at the bottom of the lobby. But then I got a popup saying I'd left too many lobbies as "not ready," though it had never shown me the button to confirm ready and join a lobby.

I've tried logging out and back in; it's still happening. Logging into a custom game works just fine.