Removing an event from Desktop Outlook does not free the time in Bookings (even a day later)

If a user adds an event to their calendar in Desktop Outlook, as expected, that quickly (within a few seconds, maybe instantly) appears as unavailable in Bookings, so the calendars are syncing. However, if the same user removes an event from their calendar in Desktop Outlook, those changes don't seem to update and make that time available again in Bookings. This is happening with all our users including with my own calendar too, so very easy to quickly test this (assuming propagation should be near instant, as it is when adding events).

Many of our users will block out time to reserve time for uncertain meetings (when working with outside parties who don't use Bookings or Calendly or any other option, it can take a few back-and-forths to lock in a time, during which users need to reserve all possible times). Then, they remove those reserves when the actual meeting time is set. Removing these should free up the time in Bookings, but it does not. 

Another case where this is a problem is if a meeting simply moves. If it was originally set from 2-3 and moves from 3-4, then the 2-3 slot should re-open, but in Bookings, it does not.

The closest I could find to this was a similar post (I think it's the same issue, but hard to be sure): https://techcommunity.microsoft.com/t5/microsoft-bookings/meetings-deleted-in-outlook-calendar-still-showing-up-in/m-p/4048344

There were no responses to that question. Is it possible that everyone has this problem, but some users just don't care, or does removing events free the time in Bookings for other users?

Once Bookings has a time listed as unavailable, it never becomes available again after that.

What can we do? Thanks for any suggestions.