I'm starting to get a few instances of "failed to load the file. Fbx key is invalid" when trying to reimport into CC4 using the Blender Pipeline plug-in (and Blender add-on)

Usually I just have to re-export and redo my work in Blender then try again, and it then seems to work but I'm wondering... is there something obvious that could be causing this? It's a bit of a pain.

ps. I should perhaps say that yes, an FBX key is definetely being generated on export and is kept in the same folder as my FBX file. (the FBX I load into Blender and then save over when Exporting using the Blender CC add-on)

                                    

Unity Virtual Reality Developer