I had more than 4 creatures in play and was not getting the convoke cost reduction
Cards with stored mana can’t have their mana drained or raised. The last game update broke something where that also means “can’t have it’s cost reduced”.
It’s not in the release notes, so it seems to be tied to another change. I think the change for Chimil, the Inner Sun hit this mechanic unintentionally.
@Magic_PQ_Support_Team please check on this. It hits a lot of different cards.