Target container is ESX, either discovered directly or as part of a DRS cluster
After successfully migrating a workload to a VM and preparing the target for synchronization, the source workload is no longer visible in the Migrate client.
In order to resolve this issue, follow the steps below:
1. Undiscover the target VM
2. For each instance of the VM folder appearing in a datastore (housing either the VMX file or VMDK files) rename the folder to something that is not the hostname of any discovered source workloads
3. Refresh the details of the container
The source workload should be visible now. Once the target is prepared again, the source can be dragged and dropped onto the target to create a Server Sync migration.