Maven's invitation: The Feared not dropping loot nor counting completed

Maven's invitation: The Feared not counting completed nor dropping loot if click "return to town" at the moment the last boss died.

Entered the Maven's invitation: The Feared solo, got killed while fighting the last spawned boss, my explosive arrow ballistas are still dealing damage.
Wasn't aware that the boss is dying, clicked return to town.
Returned via portal, there are no enemies, no loot, and the portal returning to hideout is there.
Cannot re-initiate the fight nor it counts as atlas completion awarding the favoured map slot for me nor there are any loot to pickup.

Since it is my totem/my ignite damage that kills the last boss I expected that the boss counts as my kill thus awarding map completion. Even if there are no map completion awards due to the fact that I have left the instance there still should be loot dropping waiting for me to collect after returning to the instance.

A bit disappointed and maybe have to find all the five bosses again before completing my atlas.

Not a bug.

If you aren't there when the boss dies, this is what happens. This is by design and has been stated as such by GGG.

Next time, stay dead and wait for the death animations/loot drops to finish. This will happen with other fights like Cortex/Elder/Sirus etc as well.