Some bosses don't drop loot and prevent using Town Portal in boss arena after boss dies

Bug Report ID: #528913920

As mentioned in the title, I've seen a couple of instances now where I can't use a town portal out of a boss arena after the boss dies. In these instance the boss also doesn't drop any loot, although I do get a completion for the map after killing the boss.

If I run out of the boss arena, I can port back to my hideout without issue.