My T3 Nightmare key was consumed though the enemies were no more difficult than normal world T3 and I didn’t notice any having been empowered.
No additional nightmare keys dropped, where typically I have seen 2 or 3 per nightmare dungeon. This was my 2nd completed dungeon this login and the first rewarded me as expected and about my 4th since unlocking world T3.
I did see the message stating that I had empowered the dungeon before entering it.
I did unlock the aspect for completing the dungeon.
No Complete items were awarded, nor was I able to upgrade my sigil.
The issue occurred on PC