Unable to race custom painted cars

On my xbox one, used mostly offline, I can custom paint a car, “save to current car” and that car w/ custom color appears in my garage. But whenever I start a race, either free play or career, and before the race use the “select car” button, I go to my garage, click to select the custom-painted car. But instead of that car, an original showroom stock color version of that car appears on the track for either free play or career races.
What good is painting feature if I can’t ever race that custom painted car? Game has all updates to April 2023. What a strange bug, never saw that in my Horizon 1 thru 5 games. Obviously the difference is, Horizon games are developed by Playground Games, but Motorsport 7 was developed by Turn 10 studios. Can you guess which studio beats the other in game quality and features? Too bad Microsoft doesn’t fire Turn 10 and have Playground Games do everything. Forza Horizon series is so perfect, everything from handling to visual quality.