After unregistering the Service Catalog and CAEEM applications on the new EEM server and exporting the applications from the old EEM server intermittently, the approval emails to Groups are not going to the members for certain/most groups in EEM/Catalog.
Service Catalog 17.4 RU3
The reported behavior is analyzed by SE via defect DE622971 and the fix is included in 17.4 RU4.