ISSUE: PHD/UVB error - “no work started”
RESOLUTION: If it is the case that you have more than one Host and the VMs do not reside on storage available to BOTH hosts, then you'll want to deploy a new PHD\UVB VBA on the other host. If using UVB, make this new UVB an Engine by adding it to your Presentation (CONFIGURE > Add Appliance) and assigning storage to it.
CAUSE: The engine on one host will not have access to the other hosts VMs for backup unless they're on shared storage. This is also true if you have chosen to use the Local storage on the host.