[geetarman]

Take the scope and mount off and take a careful look at ALL mounting surfaces and check for burrs.

If you find some, carefully stone them smooth. If not, remount the elements and see if POI changes.

What you are describing sounds like something interfering with the surfaces mating up.

Just taking the thing off and remounting may make all the difference in the world.

The only other thing that comes to mind is an inaccurately machined base or rail on the rifle. I am guessing the problem is not that. Look for the simple things first.

The fact that everything is new points to junk somewhere in the mounting surfaces.