Hi Tommy,
Thanks for using the tool.
If you are using VC server to move vapps from FC LUNs to NFS datastore and if you have vCD actively managing the VC server, the lctree tool should just work fine.
Can you make sure that the VC server and vCD services are working fine and VC is showing the storage usage of VMs and NFS datastores properly?
Thanks,
Sandeep