I have had this issue before and after a day it suddenly fixed itself.
I join/host a game, i see the ingame lobby with a "Connecting" screenand a "Loading" text top right of the game lobby. I can type in the chat, but i cannot close the connecting screen to x in, i am left without choice but to close the game down by hitting "Abort connect".
I have tested proxy/ports all ok. Have also checked the file integrity of the game via Steam (no issues).
Logs provided.
Thanks.