Hi @GISHelp
When you refer to Field Maps application are you referring to Field Maps web or Field Maps on a mobile device?
If you are referring to Field Maps web users can only view maps that they own, which includes administrators. If that was the case do you know if users can view the maps in Field Maps web on the accounts the maps were created?
If you are reffering to Field Maps on a mobile device you may not be able to see one of the maps because it is either not shared with the account that is being used to log into Field Maps or the setting "Use in ArcGIS Field Maps" is not selected. That settings can be set by the map owner in ArcGIS Online under settings for the web map.
If those don't work please let me know and we can troubleshoot further.
Alix