sync calendars to current day

[Jeffrey5]

I have a few listings and have noticed the calendars are not only not syncing correctly as in not always the right number of days booked but also the calendars seem to be synced sometimes days ago and do not update on their own which is what I thought syncing was all about.  What triggers the sync? I would assume a change of some sort but it isn't reliable.  Has someone figured out a way of getting the calendars synced to the current day?