No answer found, it wasn't an actul ACL problem (file ACLs of the offending VM were identical to all other ones), probably something got stuck in the VM configuration.

Deleting the VM, re-creating it and re-attaching its VHDs completely fixed the problem.

Hyper-V virtual machine can't be migrated to a specific host in the cluster
Why did Lucifer care about Mammon crossing over from Hell to the real world?  Before coming up to drag John (literally) to Hell, he makes a detour and sends his son back to presumably prevent Hell on earth.  Why would the master of Hell not want to expand his domain?
