This issue is resolved in NSX-T Data Center 3.1.2, see
VMware Downloads .
Workaround:
Some environments may have multiple vmkernel interfaces on an ESXi host configured for management.
For example the following configuration used by VxRail would experience this issue
vmk0 - management - IPv6 address only
vmk2 - management - IPv4 address
To workaround this issue, using the vSphere client uncheck management from vmk0 and retry the migration.