"Imunify agent is not running"

First of all, try to check the status of the service via the command line using the following (based on the service you are using: Imunify360 or ImunifyAV(+)):

In case the issue is still the same after 60 minutes, you can try creating the backup of the Imunify files and do the service restart to force the sync process:

# service imunify360 stop
# mv /var/imunify360/files /var/imunify360/files_backup
# service imunify360 start