The Item rewarded from 2500 M+ score is currently bugged and not providing the enhanced mythic effects on tier set items.
My alt has the appearances, but my main (also above 2500 io) does not have access to the apperances.
Experiencing the same. Used on my main and did not get any myth appearances added. Logged out and back in and still not seeing anything added.
This seems to have been fixed today (at least for me). Upon logging in I received the missing appearances.
I’m also having this issue, it seems that any normal piece that I had unlocked before I used the voidstone didn’t register.