I have used Spazstix on a wide variety of surfaces where it's a superior aerosol paint that will stick to just about anything, not only is it waterproof but it's also fuel proof where nitro fuel won't degrade the finish ;)
The OP has an RC Truck in his avatar and states:
"I recently got back into RC stuff and I usually use spray paints for the bodies and haven't had any problems. However, I recently tried to paint the interior of a truck and this acrylic crap wouldn't cover anything."
The problem is he's using...
My go to is Spazstix
https://spazstix.com/
My backup is Duratrax:
https://www.horizonhobby.com/search?q=duratrax+paint&prefn1=brand&prefv1=Duratrax&srule=best-matches&sz=24