Me and my friends have had the problem since a few days, can’t join any instance we’ve tried so far (AC, CM and TA).
We try to go into the dungeon, but the prompt for anyone leads to nothing and we’re left stranded. Others try to go in and get into their own instance, not together with the rest of us.
We tried to create dungeons with different leaders, walking in, going via popup and everything led to nothing at all. Sadface.
This happens on the server Desolation (EU) and we’ve tried it early in the day, at the afternoon and in the rush hour times between 5 and 8 in the evening.