has anyone had good luck with rolling rustoleum paint over or even using it under rustoleum brand paintable undercoating?

i didn't get to fully finish my car, and i have surface rust showing through the areas where i used spray undercoating.

my process for undercoating:
sand regular and prep as regular
put down 2 thin coats
spray undercoating
following directions for time, follow up with multiple coats of undercoating


i drilled holes in my new fenders to mount some trim, and touched it up with white paint. the paint never seemed to dry over top of the undercoating, turned brown, and i still wound up having rust around my drilled holes (in my new fenders!).

i planned on doing two tone on my older fox hatch and have a color mixed to match the original lower gray, but now i am wondering if the paint will just even change color, not adhere, or even rust from the backside-out......

has anyone used other products?
anyone try the spray bedliner with rustoleum roll paint?

thank you for any tips and advice.