Narset, Enlightened Master casts creatures
Opponent cast Silverclaw Griffin off a Narset, Enlightened Master trigger
Had the same bug, I flipped an Emrakul on my opponent and 3 others creatures in a 5 color deck (Drafting cube)
Also had this today 2/12/2021 - Was able to cast Emrakul...
Also had this issues August 5, player cast Enlightened Ascetic using the ability.