If I die once in Uber Incarnations, can't go back in due to instance DC

https://youtu.be/DQuqUonAGoE

On Uber Incarnation fights, if I die only once, can't go back in because game keeps DCing me. First join works just fine. Also tried Uber Elder and it works normal, can join multiple times if I die.
I tried changing servers but nothing works. Extremely frustrating because not only I spent some few divs on the invitations, but also because I'm just trying to complete challenges. It happened on one or another fight with another boss but can't recall what fight it was - not including one other incarnation that happened the same thing but didn't record that one.
Above is the clip I made on that issue. Server is Sao Paulo, BR.