Teleported to entrance mid-boss fight in Blackheart Haven

Alchemical

I've seen almost all the bugs this game has to offer, but this is a new one. I was doing Blackheart Haven and while doing Roost Mother about mid-way through the fight 3 people were suddenly teleported to the start of the area - not the start of the entire dungeon even but just to the beginning of that section. We tried again and once more two people were teleported away. Nothing else strange happened, but it's certainly an unprecedented quirk. It was also absolutely not your standard high ping teleporting, since it happened to the whole party at the same time.

This happen to anyone else or in any other dungeons?