Omen of the Hunt is bugged and not consistently working

Just killed an enemy possessed by the Spirit of the Owl in a map while having a stack of 4 Omen of the Hunt activated in my inventory. An omen was used and the stack decremented from 4 to 3, but no spirit reward was dropped, and Delwyn sat there bugged acting like the spirit was still alive even though it was no longer spawned anywhere on the map.

So, it seems like something bugged out with the spirit death. The omen was consumed but no drop and Delwyn not recognizing the spirit was killed and still seeing the "Owl-touched" tornados spawning despite all enemies in the area being dead and the map being empty and basically done.