We were fighting the Jackal in the circuit, it was I think around the 10th round or so (if it has any relevance), can't remember if we already fought it in a previous round, I seem to recall not, but anyway, it went like this:
First phase went alright.
Second phase went alright, except that after performing the finisher, the Jackal disappeared, but instead of reappearing in another location for the third phase along with minions, after a brief delay (about 15 seconds, not sure) it reappeared in the same location as phase 2. I didn't see if there were minions too, because I had already gotten far from there; if there were any, my companions killed them very quickly, and when I got back there we finished the Jackal.
But then it disappeared and that was it. The circuit did not progress to the subsequent round.
We waited like a couple of minutes, confused, waiting to see if the end of the current round got registered, but nothing happened.
The host sacrificed themselves by quitting (losing all progress), and after host change I found myself as host, with another player from before, in what seemed the start of the Jackal round from the beginning (it had all health). Except that it spawned along with minions from the start (where normally it is alone in the first phase), and after we beat the first phase, the round had a brief delay again (making me fear to have to quit), but then progressed.
Of course we extracted, before encountering further bugs, but the former host had their playtime completely wasted (and I risked myself the same fate).