Apologies if this has been posted elsewhere. I did a search and couldn't find anything. Some of the Class 66 locos on the SEHS have no livery and appear to be an incomplete sky-blue color. Is this correct, or do I perhaps have a corrupt or missing file somewhere? Not all the 66's are like this, just a few.
Have you perhaps messed around in the Livery Designer before? Liveries you create in there will automatically appear on your routes.
Aha! That was it. I didn't even realized I had saved a test reskin. Thanks for the tip! Here I was testing functionality for DTG and didn't even know it.