Before adding the volume you were able to LM the VM between the nodes?
can you test this and tell me the results.
1. Shutdown the VM on node where is it running, let me call it NodeA and try to live migrate it to NodeB and see if it succeeds. If it does try bringing it up on NodeB, see it succeeds.
2.Try to quick migrate the VM from NodeA to NodeB and see if it succeeds.