Center Cap Problem with plastic caps Please help.

[Long Box 2k]

I am having a problem getting my plastic lug nut caps to grab which holds the center cap on the chrome clad factory wheels. I hear about this but have yet to find a solution. Someone must have encountered this. I see where some replacement caps will only work on the silver painted rims so I thought someone may have replaced mine at some point. I pulled the cap off and it is the factory cap with the date matching the truck. I have tried replacing the lugs thinking maybe the taper angle was worn over the years and I have also bought new dorman caps. This combination doesn't grab either. They just won't go in enough to thread onto the lugs. I am thinking now that maybe there is some corrosion under the clad skin the is pulling away from the wheel although I don't see any signs of this. Has anyone found an answer to this? Please help. I am about out of ideas.

2000 Silverado

6 lug with chrome clad wheels. This is the dome cap not the flush cap.

You can see the cap loose in the photo.

Thanks