Policy Install to Fortigate failed with - entry not found in datasource

[netserv]

Good Morning, 

            Currently I have encountered an issue syncing my fortimanager policy with my fortigate unit. 

According to the install log (Attached), i am getting the error "entry not found in datasource".  This error is for a group called 

"Head_Office_Executive_Devices". 

this group is a group that is managed on the fortigate (see attached screenshot). 

Is there any way that i can resolve this synchonisation issue as the users of this group no longer have access to WiFi as the fortigate is not authenticating them via their Mac addresses because this group is not on the fortigates local policy because its not being synced by the fortimanager. Therefore when users try to connect they are greeted with the guest captive portal to login. 

Any Assistance is appreciated, 

regards, 

NetServ