Recently had a few Zerto Recovery Groups ( VPG’s ) came up with the state 

Recovery is possible. (0%)

Connecivity to the VM’s where ok , and when I ran through the Wizard after Editing the VPG is came back with all ticks. A reboot of the server and SCVMM server did not clear the issue either

In the end we had to perform a “Force Sync” to resync the delta’s