Issue adding new HyperV virtual switch in SCVMM 2012

We have 3 Hyper-V hosts running Server 2012 R2, majority of the VM's are showing "Unsupported Cluster Configuration" in SCVMM, additionally there is no Virtual Switch listed under Virtual Switches in the cluster properties.

So I started investigating each of the hosts in SCVMM and also checked the virtual switches on each one. That's when I noticed there were no physical adapters assigned on hosts 1 and 3 - host 2 appeared fine. Trying to add them back in again caused the SCVMM console to crash.

Looking at the HyperV config on each of the hosts in Hyper-V manager, and also Teaming, the config is all there and we can live migrate VM's using Failover Cluster Manager. So it appears that SCVMM is the issue.

I removed the virtual switch from one of the hosts using SCVMM, and attempted to add it back again, however the new virtual switch did not save. After clicking ok and then going back into Virtual Switches, there are no virtual switches in the list. I tried a second time, same result - nothing gets saved.

Any help to resolve this would be appreciated.