The images should explain it all, but that helm dropped for my Evoker on the/my first Doomwalker kill of the Anniversary…
EDIT:
Snapshot ID is:
b6da187ccf9c4261a417b32425389ed3
I’ll take a look – usually this means they hotfixed in some bonus IDs needed for those items. I did an update on Wednesday but it looks like they did another little patch, so we’ll scan that and it should fix it.