On the C-7 hubs, each device on the zwave details page has a status, and a refresh button.
What exactly does hitting refresh do (I have my guesses, but thought I would ask)? I ask because there are multiple devices on my page listed as unknown or not responding, and hitting refresh does not change that. They are all mains powered devices - no battery powered devices at all on the hub.
Yet those same devices work perfectly on the hub from the device details page. So I don't think there is actually a "problem" per se.
For what it is worth (nothing, likely) I did a zwave repair, and everything shows as OK right now,
Side note, I realized I have a few more S2 capable devices (GE/Jasco) so I'll try pairing them tonight. Just a few devices, but it is another S2 data point at least.