Hyper-V cluster some VM's error with status code 156

We have a Hyper-V cluster with 3 machine nodes, using a CSV connecting to an EMC VNX on two luns.   We have two cluster volumes coming from 2 Luns off the VNX. We have two policies one for vol 3 and one for vol 4 vdh's. Each of the policies limits to 1 job per policy.   All of the vhd's on vol 3 backup with no issues.  Some, but not all of the vhd's on vol 4 fail with a status code of 156.  Of the systems that fail, they reside across all three hosts.

The bpfis log shows EXIT STATUS 4207: Could not fetch snapshot metadata or state file.

We had this happen a week ago and cleaned it up but it's back now and need to figure out why this keeps happening.  Any suggestions would be greatly appreciated.