I'm trying to leverage some of the animations that ship with the TwinBlast asset from Paragon. I want to use them as animation montages triggered by the Gameplay Ability System. The montage plays fine in the montage editor, but when I try to invoke the montage in a Blueprint (even the character Blueprint), nothing happens. I've tried adjusting blend in and blend out timing, but that had no effect.
For the montage to play properly, the slot on the animation sequence must be changed to "DefaultGroup.UpperBody":
This was confirmed by the following videos: