I had some jujube pits in the fridge from earlier this summer/fall. Some were from Chinatown and others were from Raf (thanks!). The presence/absence of seeds was interesting:
Sugar Cane (Raf): Maybe 70% had viable seeds and most of the rest at least had small or shrunken ones.
Li (Raf): Maybe 20% had good seeds. And those 20% were clustered in the largest pits. If it had a large pit, more than half had a seed (but not all the big ones).
Li (Chinatown): I went through a handful without finding any seeds. I then checked the largest 4 I could find and still no seeds.
What I take from this is that Sugar Cane needs pollination, while Li will set fruit without any (like the grower who supplies Chinatown). Even when pollinators are present (Raf's place), only some of the fruit gets pollinated and it isn't required.
I kept all of them in the fridge, with wet paper towel wrapped around them. And it was pretty icky.
One thing I noticed was that often the stratified ones crack down the edges, leaving two perfect halves, compared to the freshly harvested ones which crack more irregularly. When they crack in half, the seed often gets stuck in one half and is hard to pry out.
After destroying one, I accidentally found the answer by dropping it. When it hits the ground, the seed often pops out, at which point you just pick it up. I tried to pick up the shell too, so that I won't get complaints about the kitchen floor...After I noticed this trick, I used it repeatedly. Sometimes, a tough one needs to be dropped several times, occasionally with a bit of force. From what I can tell, none of the seeds were damaged by this. If they were, it probably wasn't as bad as what I would do, trying to pry it out.
The arrow on the left is a Li, which is still in the shell. Note that the Li are much bigger than the Sugar Cane seeds. Also, there are 2 seeds from some rootstock fruit on the right (one was twins). They are much smaller, but I'm guessing that a high percent are viable.
I divided the Sugar Cane into two batches because there were two different paper towels in the bag and the 2nd one seemed to have slightly more elongated seeds. I'm not sure that they are different, but they could be.
Here's a pic of what the So seeds from October look like now. I've got at least 10 which have germinated.