External model update turns placed models invisible

[Guppy]

As per subject.

 

Steps to reproduce;

1. Export model from blender
   
2. Set up material
   
3. Place model in scene to inspect
   
4. Re-export the model
   
5. observe that the placed model is now invisible with and has no material (but will still be rendered in when you run the game)
   

 

Re adding the material to the placed model does noting, only deleting and replacing seems to work