We are having the same issue. Multiple networks the only thing I can do currently is delete an existing view. Support was nice enough to send me the following email after 2 days of back and fourth with them including a phone call. I'm ready to send back all 200+ cameras however my boss is not.
We are aware of the issue with Video Wall in our MV devices. Our development team is working on this with priority. The issue is reported even in the latest MV4.0 and hence a Firmware update will not be a fix at this stage. We will update you as soon as we have this issue fixed.