Seems likely to be some communication issue on the target site between VR > ESXi > datastore. Maybe VR appliance can't communicate with the ESXi hosts on the target site - I would say try a reboot of VR, and verify you have connectivity from VR to the ESXi hosts over port 902. Is it possible there were any IP changes on the ESXi hosts?
Otherwise, could there be some storage access issue on the target site? Maybe some hosts not able to connect to certain datastores?.