When working with Advanced Group policy management and using a service account, you need to give the service account rights to all existing GPO’s if you want to have them controlled by AGPM.
To do this easily you can download Group Policy management Console Sample Scripts.
Once downloaded and installed you can use the script GrantPermissionsOnAllGPOs.wsf.
In order to grant the service account (AGPMsvc.agpm) FullEdit access to all existing GPO’s you can use the command:
cscript “c:Program Files (x86)Microsoft Group PolicyGPMC Sample ScriptsGrantPermissionOnAllGPOs.wsf” “AGPMsvc-agpm” /Permission:FullEdit
Just not fun doing this on every GPO with the GUI