I've been working on getting several VMs exported from a single, stand-alone Hyper-V server to a Hyper-V Failover Cluster. When running the Import Wizard in the cluster I kept getting a general permission denied error. Searching the internet turned up nothing. And a post in one of the forums only turned up a couple of work-arounds.
What I discovered is that in a Microsoft Failover Cluster, one machine/node is the 'owner' of the Cluster Shared Storage. It is on this machine, the 'owner' of the shared storage, that the import operation needs to take place. Apparently because of the permissions that the 'owner' has compared to the other machines/nodes in the cluster.
In doing my search for a solution to this, I also came across a list of "Hyper-V Gotchas" over on TechNet, and have since added this little pearl to the list.