I have a couple of GeoFence Synchronization Rules that seem to work when importing new features that were added to the feature service since the last sync, but they do not appear to detect when the feature backing a GeoFence has been deleted from the feature service. I would expect it to do this and automatically delete the corresponding GeoFence. Does this functionality exist?
I had a customer recently run into the same issue, and then I found the following bug:
BUG-000089545 : GeoFences are not synchronized when a feature is deleted from a feature service.
It looks like this bug is still relevant at 10.8.1. I did some testing and found that the only way to remove Geofences through the GeoFence Synchronization Rules is to designate a date field for the Time Extent End parameter.