ATTEMPT TO JOIN QUEUE FAILED

My TFT ranked game failed to load in. The client got stuck at an empty client window and didn't transition into the usual loading screen. I exited and opened the client again, hoping I could reconnect, only to find that the client is back to normal, as if I'm not in game. I tried to queue up for another game again but an error msg saying " ATTEMPT TO JOIN QUEUE FAILED " popped up. Now, I can't reconnect to that game that failed to load in, and I can't queue up for a new game either, regardless of queue type.

I tried to sign out and in again, I even restarted my PC, but the problem still persists. The client still thinks I'm in game, for some reason, while it's behaving as if I'm not in game and allowing me to browse the client as usual... it's just that I can't queue up to any game mode, atm.

This happened more than 40 min ago, btw, and I still can't queue up again!