I haven't heard or seen of any discovery issues which would prevent you from provisioning to any existing vServers, nor would prevent you from provisioning to any existing controllers which are visible in VSC.
In the case of the vServers, I would think that using the "update" function would allow them to appear faster for either provisioning or M&HC discovery.
For the hosts/controllers which are not appearing in the M&HC diagram, I would think that we would need to review the VSC logs, with examples of which of the hosts/controllers aren't appearing, including a timestamp at which point they weren't appearing.
Try capturing the following for analysis:
name of the host/controller which isn't appearing in M&HC/P&C, and "where" it didn't appear
timestamp of when the host/controller didn't appear
If we aren't able to help quickly over the forums here, we'll go ahead and get you a support case to continue troubleshooting and investigate further.
Would you be able to upload the VSC logs? I'm curious to see if there's maybe an inconsistency in the ZAPI calls being sent, or the subnetting is somehow coming into play here (although neither should be true, it will be easier to see in the logs).
In case you haven't generated them before, you can just open your vSphere client, click on "Home" -> "NetApp" -> "Monitoring and Host Configuration" -> "Data Collection", then choose "VSC Logs" and hit "SUBMIT".
You should be able to upload the full bundle to this thread, but if it's too large then ping me offline and we'll get a support case going for you and upload/analyze them from there.
Only the interfaces on the 11/12 subnet were ISCSI enabled. The System was added to VSC with the Mgmt Interface (e0a).
When trying to deploy an ISCSI datastore via VSC I noticed it was stuck. Checking on the console I noticed that the ESX hosts wanted to log in via the Mgmt interface, which didn't have ISCSI enabled. Only after enabling ISCSI on the Mgmt Interface the provisioning succeeded. Traffic only flows via the ISCSI interfaces as far as I can tell. (That's how I configured it in ESX...)