[2019] Bank Headquarters Bug (Invaded/Heroic)

Has anyone else had an issue completing Bank Headquarters (Invaded/Heroic)? Yesterday a friend and I were on XBL doing this mission. After clearing the vault, there was a single mini-tank upstairs. It had no health, and although we could shoot it and use skills on it, it wouldn’t die. We were stuck and couldn’t continue. We tried fast traveling, using grenades, specialization weapons, but no luck.

Today it happened again. This time we tried to quit the game and come back in to see if it would allow us to resume, or even reset the room, but no luck there either.