Baking - Error 'nonetype' object has no attribute 'action'

[slippystance]

First off, great addon!

And it works until the very last step of baking....

Mocap data (403 frames) and an imported bvh in rest pose (403 frames)

Retargeted mocap data to bvh - success and aside from 2 mapping tweaks (left and right shoulders) nothing else needed.

Attempted "Bake into Action":

Error result: