Additive Layer Broken

Anyone know what might break additive layering? We’re using 4.5.1f. The character was exported from maya as an FBX. It is a human using the humanoid rig. The hierarchy is standard, except it has an empty transform at parent, which doesn’t seem to affect the humanoid functionality.

Epic quest to figure out additive blend layers:
(spoiler, they don’t work)

test 1

test 2

test 3

test 4

test 5

test 6

Found the break

Getting warmer

After these videos, I did more work. Turns out that additive layers pretty consistently cancel the first keyframe of an animation on it. You have to blend over this weird trait, and it makes poses on additive layers useless.