We migrate on demand as and when we open the models.
So far I have clicked 'No' on the migrate appearances prompt, as I clicked yes once and everything turned yellow!
We didnt migrate our standard content centre files as far as I remember! We've been to busy!
When we moved from old 10 to 11, or 11 to 12 we never had any of these problems before, so we didnt anticipate them! We have always been open to open the models and migrate when necessary.
Thanks for your help!!
I'm still unsure as to what caused this in the first place; you'll notice that the "welded appearance" bolt has a Material of Steel, Mild & an Appearance of Default. The proper looking bolt has a Material of Steel, Mild and an Appearance of Steel.
If you view the assembly using the Realistic view mode instead of just shaded then it will appear correct. I suspect this will be the case for your other parts too.
Do you recall if when you first opened the data, whether you had configured a custom appearance library or if you were just using the as shipped versions ?