When adding a thread to the forum calendar, if the thread is a sticky the date becomes a hyperlink, but the calendar does not show the thread title, or any other text in the box for that date. If the thread is not a sticky, the thread title is shown.

I can fudge it by adding a non-sticky thread to the calendar with a link to the sticky thread I wanted to add, but as with most fudges, it is not a particularly elegant solution.

Is this a bug, a 'feature', or a config issue?

I believe the calendar only works with normal topics.

All forums have the calendar enabled. I am linking the sticky and the non-sticky in the same forum - the non-sticky works fine, but the sticky will not show the thread title in the calendar. If I edit and make the sticky non-sticky, the thread title appears in the calendar. If I make it a sticky again, it disappears.

I edited my post.

Any topic's link will help, man!

I don't know i have never seen this before as i have not used it
but the better system is now online here >> https://help.forumotion.com/t153199-new-functionality-the-events
it's a much better way to get your events out there to your members