The ones NOT showing up take place before midnight, the ones that DO show up after. Could that be making the difference?
I doubt it, but that's easy to test. Just change the cron expression of a job that does show up and see if it disappears from the calendar.
Since it's working for some jobs and not for others, there has to be some kind of difference between the jobs. Unless I know that difference, I can't reproduce the problem and fix it.
One way of figuring that out would be to create an empty Free Style Project with nothing in it but a cron expression. That should show up in the calendar. Then, step by step, adjust that project to match a job that doesn't show up in the calendar. At some point the project should disappear from the calendar and we know what the difference is.
Much of what I wrote in the other ticket (JENKINS-54037) also applies here.
In addition it would be helpful to know the exact cron expression that you're using.