Following a power down of our Hyper-V cluster, about half the virtual machines  (VMs) would not start.  Looking in Failover Cluster Manager showed  the VMs couldn’t start because the machine files were missing.  I looked at the Storage summary, but the cluster shared volumes were present and had a status of online:

This was odd, Failover Cluster Manager was saying the VM files were missing, but the disks were online.  I expanded the cluster shared volumes (CSV):

If you look at the CSV paths, you’ll see the path for Cluster Disk 1 is C:\ClusterStorage\Volume1 and the path for Cluster Disk 3 is C:\ClusterStorage\.  The reason the machines wouldn’t start was because the Cluster Disk 3 path was incorrect.  It should have been C:\ClusterStorage\Volume2.

I right-clicked on Cluster Disk 3, chose “Move this shared volume to another node” and selected one of the other cluster nodes.  When the move had completed, the path was correct and I was able to start the VMs.