Just noticed this issue on some of my units on the Bridgewater-Brunel server. Units appear correctly in Southern and BR green but in BR blue there is no skin for the motor cars.
(https://i.imgur.com/t562vME.png)
(https://i.imgur.com/jPzFGoa.png)
(https://i.imgur.com/HL8IZ7k.png)
Thank you for the report - I have re-rendered this and the fix should be available in the next nightly build.