I also had severe fruit drop on all of my plants, two potted ones and one inground that was planted in the spring.
I had fruit drop on like 2 or 3 waves.
The inground fuyu had 3 fruit up until 2 weeks ago, 2 of them fell..
Potted fuyu also dropped around 5-10 fruits at a verry late stage, its doing the best thought and now has nice regular to big sized 12 or so fruits, of course both of the potted ones also had a strong fruit drop around end of june i think.
Potted astringent persi which i would assume is hachia variety had an ennormous fruit drop , probably 80-100 fruitlets fell at the start, slowly progressing until i was left with 5 fruits that gained in size, up to 2 weeks ago when 2 of them also fell, nice big fruits...
The 3 plants have been quite synchronized in the way they drop their fruits. I still think that i overfed them in spring so i aided for the fruit drop probably , no fertilizing for them next year!