I'm having this same issue though I tried the solutions others mentioned and literally nothing worked. I can't apply any new wraps and I risk losing my progress which I have twice already. I'm about to delete this game and never touch it again. For me it started happening after I bought a McLaren P1 and all I did was change the paint to red and it messed up my whole game ever since. I'm too scared to even play it in case I lose my progress.
I managed to fix it. What I did was remove all the wraps from all my cars both online and offline, then I deleted the wraps that looked blank (just showing a plain colour on the picture instead of the stickers and what not) then I let the game save then I quit to main menu. To avoid losing progress on ps5 make sure you quit to main menu before closing the application otherwise you'll be met with an error message when closing the app, this is what corrupts your save. Start the game back up and start re applying the wraps that show up properly in the picture. Once that's done quit to main menu again just to make sure it's saved, then manually upload your save to the cloud. As long as you close the app while in the main menu. Your data should be fine.
