I did change the load thing yeah (the second time around because I didn't initially notice it, clever me). It didn't actually break your other WAs, just some other stuff I'm using (although that's probably on their end, as a few WAs I made myself for Infested did the same). The issue remains that it didn't show up for me even when I unchecked the Mythic only option, but maybe I'm missing something obvious. SpellID is not the same (they differ presumably due to the damage), but as you say that shouldn't matter (I used both spellIDs to no avail, anyway).
If other people have used it successfully then there's something that just doesn't work with Heroic I assume (or something that clashes with my WAs), but I don't see why that would be the case. I will try it with said set of WAs disabled out of curiosity, but that won't be before tomorrow evening or sth.