Some time the best fastest and easiest way to migrate, transfare, CSV Disks to new environment is to just Expose the LUN on the storage to the new hosts\Nodes and join the disk to the new cluster without formatting it, Then just import the VM’s on the CSV disks to the new Hyper-V cluster.
When disk is turned to CSV it gets cluster Reservation ID, if you want to move it to another cluster you will have to remove the reservation first and then re-join the disk the the new cluster, First know the disk number, you can find this on the “Disk Management” window or go to CMD and type :
Find the right disk number and the from Powershell as Administrator run (for this example = disk 1) :
Clear-ClusterDiskReservation -Disk 1
After that just refresh the cluster and the will appear
More information on Clear-ClusterDiskReservation : https://technet.microsoft.com/en-us/library/ee461016.aspx