I have a 2001 American Tradition (Fleetwood) and I have always had what I think is the same issue youíre describing. On mine I believe the cause is the seal around the door is perhaps a little thicker than it should be. It seems to stop the door from fully closing using a normal pressure and speed. The door seal on mine doesnít allow the locking mechanism to fully engage as I believe it should.
My fix is to close the doors without any excessive force and without holding the latch handle at all. When the door is closed but not fully closed /lock engaged, I place my foot on the ground directly below the front/rear edge of the door with my toes pointing either to the front or back (depending on which leg Iím using) I use the outside of my leg as a lever to close the door the rest of the way which engages the latch. You will hear it click. Then I lock it with the key. Itís a pretty easy thing to do and because of the leverage you have it doesnít take much force ( just donít use your shin
I hope I understood the meaning of your issue, if not I apologize.