That is really strange. Besides that after the tickets are not available the entry in the calendar are not shown, if noticed that all expired datetimes doesn’t show up in the calendar with this, even if they are on sale.
An expired datetime is a datetime with a event end date in the past, it sounds your telling the calendar not to display expired events/datetimes, but want them to display?
Do you need screenshot from the case that the tickets are on sale but expired datetimes doesn’t show? Or other infos?
Can you add a screenshot of the datetime and ticket editor for the event please?