Same issue as described here: https://forums.playdeadlock.com/threads/cannot-enter-matchmaking-you-are-already-trying-to-find-a-match.85097/
Looks like we just have to wait until it lets us back in
Same issue posted here: https://forums.playdeadlock.com/threads/cannot-enter-matchmaking-you-are-already-trying-to-find-a-match.85097/ looks like it's been a recurring problem for awhile now
Last time it happened to me I was able to queue again after 6 or so hours even though I changed nothing.
My current head-cannon is that this only happens if you stay in a game after it's been marked safe to leave because a leaver is detected.
Both times this has happened to me is immediately...
Ran into this issue earlier today today as well. Reinstalled, verified cache the whole thing and nothing seems to fix it. I even tried using the dev console to quit match. It just went away on its own after like 6 hours