It seems like hots m3 are no longer compatible with sc2 m3 files (at least the fx stuff).
If I had to guess there were some updates to the hots art tools 
. Any chance sc2 can get the updated m3 and art tools too?
Iād love to see SC2 get the up to date HotS m3 features, but I fear that is very unlikely. Iām guessing the newer features that were never ported back to SC2 are contingent on the game engine having its graphics API upgraded from DX9 to DX11.