Thanks. I generally apply some 10-10-10 early in the season. I’ll be careful.
Your evidence re pollination may be helpful. Many forum members claim that persimmons will hold fruit better if pollinated. I suspect that this is at best true only in some special circumstances or for some varieties. My IKKJ, Prok, and Kassandra all hold fruit well despite no pollination. Your experience sounds similar.
For ex: Nikita's Gift Persimmon Fruit Drop? - #69 by Robert
FWIW, I did get seeds in a tiny proportion of the Prok fruit in one season, probably because a sucker growing from the roots of the presumably make rootstock blossomed. As far as I know there are no other persimmons within 2-3 miles and there are certainly no native trees.