Okay, got it working by redoing it from scratch and entirely renaming the .lsfx file at the point of creation in the effect editor from RS3_FX_Skills_Fire_Flamebreath_Fire_01 to RS3_FX_Skills_Fire_Flamebreath_Fire_02:
And then adding the resource for it after it had been renamed and changing the cast animation in the stat editor to 02.
My guess is that keeping the effect animation name file the same was causing conflicting issues.
With every mistake I must surely be learning...
