Final update: Athlon replaced the scope, honoring their warranty. It was a quick and easy process. The new scope zero’d at 50yd and 100yds, and in this one, the parallax markings were close to actual, just like my other Athlon scope. The scope is bright and clear, and I really like the reticle at both low magnification and high magnification off the bench with my CZ457. Highly recommended for the money. Since the match class I compete in has a dollar limit of $1500 for rifle plus scope, this gives me a very nice optic within that limit.
Since I’d already bought a 25MOA rail, after making sure the scope would zero without it, I went ahead and put it on and re-zero’d. All is well.