For me, selecting a different car through the car button always does this. From opening I went straight to a car I previously made in the Sandbox, clicked on revise, then the little car button without messing with the car. I chose a car with a different body and this comes up…
The morphs do weird things with this too sometimes.
If I choose another car through the car button after that, the same fixtures carry over
Actually doesn’t look half bad.
If I start with a car with no fixtures, the next car’s fixtures disappear. They don’t come back if you load it up normally. It also doesn’t seem to matter if there is multiple trims or just one.
Also if i edit/remove fixtures on the second car, it changes the fixtures on the original car.
Hope that helps narrow it down.