DNS zone of a domain unregistered from Legacy Plesk is not manageable in new Plesk in VPS module.
Zone management is not available in CCP and domain is greyed-out.
The issue is recognized as POA-107011.
Old properties "externalMaster" and "masters" in the APS resource of the domain DNS zone. PVPS checks that externalMaster matches with pleskPublicIP of the Panel resource, and if it does not, disables all zone controls.
Initially, when Plesk hosting was removed from the domain, DNS zone was switched to internal hosting, but the corresponding APS resource was not updated.
Later, when domain was added in PVPS, DNS zone was synced back, from APS Resource, and external master IP was set for the zone once again.
Contact Odin technical support to fix the affected domains.
The issue is permanently fixed since OA 7.0.1 + Hotfix 130015.