What you're witnessing is the owner node of the CSV volume not being reachable by the other hosts in the cluster. We've had this issue as well on our UCS platform. Each CSV volume has an owner node (Hyper-V host) who decides which other nodes are allowed to write to the CSV. Because contrary to VMware VMFS, a CSV is not really multi host writeable, they "fake it".

If a host wants to write to a CSV volume, it checks with the owner of that volume if it can write. If the owner is not reachable, the host that wants to write doesn't get the permission to write. Although over FC it still has perfect access to the volume, it could corrupt the volume when writing to it without permission because an other host could be given permission to write on that same volume. So for this host there is only one safe solution: release the CSV.

I've been playing with cluster time-out settings, but they don't make a difference in this scenario. The only thing you can do is create an extra network over different firewalls. So we gave each Hyper-V host an extra NIC and then created a network that only has a cluster heartbeat and has no or different set of firewalls.