Global Policies aren't updated from a 10.7.5 Central Control Center to a remote 10.7.4 Control Center.
All Messaging Gateway appliances in a cluster must be of the same version. Usage of differing versions is not supported.
Upgrade the older versions so that all Messaging Gateway appliances are on the same version. Once on the same version, the Global Policies will update properly. If the version is still showing an older version after update, the Control Center may need to be restarted to fully complete the upgrade.