Steps to reproduce issue:

1. Create a Humanoid (non-standard) character and rig it using AccuRig.
2. Test animations and Paint Skin weights as needed.
3. Export character using Blender Pipeline.
4. Import character into Blender using CC3/CC4 plugin.
5. Make minor sculpting changes (or not)
6. Export back to CC4 using CC3/CC4 plugin.
7. Try to test animations and they won't even show up as an option under the Motion tab.