Steps :
1) CC4 - Load any CC3 character (like Toon Figures).
2) CC4 - Modify > Convert CC3 to CC3+.
3) CC4 - Plugins > Blender Pipeline > Export ... fbx
4) Blender - Editing the fbx and export with CC3 add-on.
5) CC4 - import the edited .fbx : popup ...

"Failed to load the file"

PS: Success/No problem if step 2) is not processed.
PS: Same problem occurred if only use CC4 for exporting and importing the converted CC3+ .fbx (i.e. without Blender Auto Plugin).
PS: Facial profile / expression of the "edited" character becomes mess. This can be solved "artificially" but FRUSTRATED.