Not exatcly diagnose, but we can try to funnel your issue as much as possible to get to figure out what is causing the problem.
From what I can tell, the bug that leds to lobby scarcity is definitevely patched after this january update. So, this probably means that your issued may be rooted elsewhere aside the game, that’s why I linked you to a report on a simmilar issue to yours, this way we can get some more insights about what may be troubling your game. I strongly suggest you to also try on what MopeElTwo did. If it proves correct that is a problem with the steam account, I also recommend to contact steam and ask about any restrictions on your account.