Cars - Ford #66 Ford Racing GT 2016 - Mirrored Decals in Livery Editor (Left/Right side of car)

On some models such as the #66 Ford GT and Porsche 718, when mirroring decals from one side of the car to the other, they become permanent (unable to be flipped) and no other decals can go into that area (for the Ford GT, it’s the whole back panel on the side of the car. For the 718, it’s around the skirt). Removing the livery and going back in leaves the whole area unpaintable.

I have the same issue with my #66 Ford GT
No matter what I try, the decal only applies to the left side (facing forward) of the roof.
Have considered removing it until fixed due to feeling lop-sided.