Failed Sister of Parvos Railjack Confrontation after vanquishing Sister?

[redella]

This has happened twice to me now. I thought the first time was an anomaly, since I died right as the sister fell. The second time was clean though: I vanquished the sister, then immediately got booted out of the ship into my archwing at the entrance, and the mission failed. Now I have to do the whole mission again.
Both times I had completely different loadouts. I honestly have no idea what would cause this. I always run the confrontation solo, so it isn't ping, or host migration, or anything like that.

Also, this hasn't happened with a grineer lich yet.