I'm playing a draft deck with Golbez, Crystal Collector. Arena seems to be bugged and missed his end step trigger twice when I had 4 treasure tokens on board and plenty of creatures in my graveyard. The trigger happened once early in the game, but seems to have been skipped over the following two times. Treasure tokens were from Sidequest: Hunt the Mark if it makes any difference.
I did not lose the game, but would have been extremely frustrated if I had.