Not all jams are listed in the calendar. I suspect that the reason is that there are just too many jams to list them all. Being unlisted doesn’t mean you did anything wrong, it just means that you weren’t picked. Don’t rely on the calendar to communicate when the jam takes place.
That said…
The jam has the ‘unlisted’ box checked so I can’t see a reason for it to be excluded.
Unless you mistyped and meant “unchecked”, that would be the reason.