Mikaeus, the Unhallowed undying effect appears to not work
Mikaeus, the Unhallowed provides undying to non-Human creatures but despite the card effect displaying in the text of Crypt Ghast, upon sacrificing Crypt Ghast, which had no counters, with Ashnod's Altar, it did not return to the battlefield. Crypt Ghast was equipped with Sylvok Lifestaff, the sacrifice was made during main phase 1, and Mikaeus, the Unhallowed was played and resolved that turn, prior to the sacrifice. I found one other report on the forum from the March 10 release about Mikaeus undying effect not working. No details were provided in that case though.
On the opponent's turn I sacrificed Underrealm Lich, no counters, unequipped, and it also did not return to the battlefield. No cards in play to affect graveyard effects. Meren of Nel Toth was in play but she only returns a card from the graveyard to hand or battlefield at my end step.
Thank you for looking into this issue.