Cornerstone Mask Ogerpon ex preventing damage from Mew ex copying "Demolish"

franzpezzi_

The title basically explains it. I was playing a game in ranked mode, my opponent had Cornerstone Mask Ogerpon ex in the Active, I promoted Mew ex, copied "Demolish", knowing its damage goes through Ogerpon's ability due to the attack's effect, but hey, who would have thought…A BUG! No damage went through. This is basic card interaction, like, read the cards, make a decision, execute it, and the code executes it in a way that contradicts the wording and the rules. This is not acceptable.

Pokémon342548

What Pokémon is Mew ex battling with?