It's probably either your door strike or the strike plate on the frame. I'd first make sure the strike and plate are even with each other. Once you make sure they are in line with each other, you may want to gently pull the outer edge of the strike plate with a screw driver out so it sticks slightly further out more from the frame than it does now.
When I switched from factory door locks to RV Lock electronic locks, I went through this problem same problem with our TH.
2015 XLR Nitro 30FQSL
2015 F250 King Ranch