Abyss in Valdo's

When one of the Valdo's requirements is Abyss, most of the time, the Abyss encounter bugs out, locking the player from the Valdo's Map reward, since the Abyss encounter technically didn't end.

What has happened to me, 3 or 4 times at least in different maps, in the last part of the Abyss, when all the monsters die, the chest doesn't spawn, meaning the Abyss didn't end. Even though the Abyss does not continue, it just finishes the last leg, but no chest appears.