ETA: In regard to your zeroing adjustment - the ATACR 1-8 on an LMT MWS with a 2.625" height over bore required 4.6 MIls of elevation for a 36yd zero.
Just as an FYI to your image quality issues, I sent my ATACR 1-8 back to NF, as the image resolution/focus/clarity was horrible at max magnification at around 125-150 yards and anything further. Oddly, at max magnification, I was able to clearly resolve and focus images as close as 17 yards with the reticle always in focus.
I compared the image to all my other scopes, including a Kahles K16i, and none of them exhibited this same issue. (Granted aside from the Kahles and an NX8, they're all ATACRs with higher magnification and parallax adjustment.) Looking through the Kahles at 6x, I could readily read/resolve wording on a range poster at 300 yards - not so with the ATACR 1-8 at 8x.
I messed with the diopter to verify that wasn't the problem, and it did not fix the issues. (I have 20/20 vision, and have never needed to adjust the ocular from factory settings on the 5 other NF scopes that I own.)
I couldn't really extract any specific info from NF about what they did, although they did agree the clarity they would have liked to see wasn't there, but they did *something* and now that I have it back, it's perfect. Images/focus/clarity are readily resolved at the closer 125+ ranges and to infinity. (within my eye's capability of course)
There is some glue reside at the objective lense seam - so I'm *assuming* they either replaced a lense, or adjusted the fixed parallax.