I've tried running 2 custom championships, 1 with Formula Ultras and 19 opponents, and another with DPi and GTE... in both cases an AI driver took the same livery as I was using. Not a huge issue really but it's a bit of an immersion breaker.
There has been 2 updates since I posted this and it's still an issue even though like 6 months ago it was claimed in a changelog to have been fixed... Does anyone know why this is still an issue if it was 'Fixed'?