So since the newest patch I started encountering this particular bug. After Clearing an instance and resetting if you port to it from a player owned house there is a high chance that you get an endless loading screen that forces you to Alt+F4.
For example, my guild is progressing Asylum Sanctorum. We clear the instance and port out. I, as group leader, reset the instance by changing difficulty from Veteran to Normal and Veteran again. The group goes to a player owned house to use the Ayleid Well to restore full ultimate. We then port in back to Asylum Sanctorum trial and then where the bug happens. There is something like 1/4 chance that someone will get the endless loading screen and is forced to restart the game. Quite often we got 3-4 players being forced to restart.
Some other things we noticed that might help:
You know that you got the endless loading screen if the loading picture is of the place you were porting FROM and not INTO. For example, when you port into Asylum your loading screen should be a picture of the trial, but if the picture is of your own house you might as well Alt+F4 since it wont ever end.
From what ive experienced it happens only if you visit a player own house before porting to trial. Our group tried to leave trial, reset it and then port back in without visiting a house and we have not experienced the bug (thou we might have just gotten lucky).
You can get bugged if you try to port somewhere else and not just to a trial. Once after resetting the instance I tried porting to Vvardenfel instead of to a trial and I got the same bug.
I have ewxperioenced this bug while doing Asylum Sanctorum and Sunspire and my guild member had it in Cloudrest, so it is not limited to one place.