How i solved infinite loading screens before the hotfix
For whatever reason i can not comment in the dev post about it, i will do it here because people keep reporting the hotfix didn't help them, so here is what precisely happened:
I was doing grove challenges with Trickster without problems but pretty bad performance until i tried to do the Halloween Hook challenge which progressed to 2/3 hooks after the match, from there i failed +10 times in a row to load into a match, so i tried a rift challenge with Trickster, same result, then i tried without active challenge and had no problems loading into multiple matches, then i reselected the Halloween Hook challenge but tried it with the Demogorgon and it worked and i completed the challenge, from there no more problems for now.
Hope this helps finding the issue. As i have seen multiple claims that infinite loading does not occur without active challenges it's likely the problem lies there.