We have had occasional reports regarding a map that mysteriously goes missing or becomes corrupt. We cannot stress how important it is to have a scheduled backup of the maps enabled. If you haven't already enabled a scheduled backup, please go to Edit > Server Settings > Map Backup and enable this feature. 

We recommend to select "All" for the days of the week. 

Start time - Anytime outside of your scheduled hours of operation.

Maximum backups - Recommended 28. This will allow you to have a new copy of each your maps for 28 days before it starts to overwrite them.