I’ve noticed the same thing on Shanxi Li- both wrinkled and bumpy. It often sets a lot of fruit, then drops most of it. I’ve noticed that the ones which are dropped are generally not the shiny ones.
Here’s a post with pics from 3 years ago:
While all jujube can drop some fruit, Shanxi Li is one of the worst. You think you’ve got a decent set and bam…only a few left.
I have single trees with that many varieties 
Though it does complicate things a bit. I try to keep it down to 5 now. Original and roughly each compass point.
I was at one of my poorest performing locations yesterday. It has pretty good sun exposure (the shade in this pic is around 5:30pm), but tends to be too dry and has delayed the establishment of the trees.
The below So is the largest. It was planted in 2018 and most of the others from the same year are about half as big. Spread over the tree is 5-10 fruit.
That 5-10 fruit doesn’t count the Bok Jo graft. It is covered.
None of the other trees have much in the way of fruitset either (even good producers such as So and Sugar Cane). A few per tree.
This is another example of why Bok Jo is such a good variety for people to start with- you get fruit much more quickly.
At another site, some of the girdles have already healed. I wonder if that mean I didn’t make them big enough, or if they have done their job in ensuring earlier/heavier fruit-set.
For this one, I’m most interested to see if the Sugar Cane ripens even earlier, as moving the start of the season up is more important that moving a mid-season variety to early-mid.
Sugar Cane:
