Unable to add or live migrate VMs on new machine added to cluster

Had 1x 2012 R2 machine (call it A) set up as a cluster with another 2012 R2 machine used for shared storage. Finally got a second machine (call it B) to add to the cluster, added the machine, passed, showed up in the cluster, but I cannot live or quick migrate machines, or create VMs on A from B or B from A.

Live migrations (going from B to A) fail with:

Live migration of 'Virtual Machine TESTVM' failed.
Virtual machine migration operation for 'TESTVM' failed at migration destination 'HOST-A'. (Virtual machine ID 0D1A3F2C-7623-4D26-A5B9-71F88599BE1C)

User 'NT AUTHORITY\SYSTEM' failed to create external configuration store at '\\SHAREDSTORAGE\vms\TESTVM': General access denied error. (0x80070005)

Failed to set security info for '\\SHAREDSTORAGE\vms\TESTVM\Virtual Machines': 'General access denied error'('0x80070005').

When I try and create a VM on A from B or B from A I get:

The operation failed.

Failed to create external configuration store at '\\SHAREDSTORAGE\vms\TESTVM': General access denied error. (0x80070005)

User ‘DOMAIN\Administrator’ failed to create external configuration store at '\\SHAREDSTORAGE\vms\TESTVM': General access denied error. (0x80070005)

Went so far as to set the share permissions on \\SHAREDSTORAGE\vms to Everyone full control and Everyone full control on the NFTS permissions. No change.

If I am on A and create a VM on A in either Failover Cluster Manager or Hyper-V manager it works just fine. I can go to \\SHAREDSTORAGE\vms from either machine and create files\folders\etc no issue.