I've gotten this bug 4 or 5 times now. It has never happened when solo queuing, only when playing with friends, but it doesn't happen 100% of the time when playing with friends. I'd say it's a coinflip on if it'll happen or not.
I'm on windows 10 with a xfx 5700 xt raw 2 gpu and a 5900x cpu, if that helps at all
Edit: I never closed out of the game and after failing to connect a half hour ago and waiting out my ban for 'leaving' I finally got the loading screen bug again but this time solo queuing so I guess if you get it, close out of your game and reopen it. also, while closing the game it stopped responding and I had to control alt delete it to close it. someone in a different thread also said the same thing about their game not responding so I figured it might be useful information