GF resorted to class problem determination:
- Any obvious setting wrong? - No
- Any problems with WiFi - No
- Any known problems reported on internet? - No
- Close it down and retry - any better? - No
- Upgrade IOS to latest version - any better? - No
- Is it working from the iMAC? - Yes, but that's a different interface.
- Does it work from the other iPad? - Yes !!!
Ok, so the problem was isolated to SV's iPad, the question is how to solve the problem. GF erased the app entirely from the iPad and re-installed it from scratch.
Everything now seems to work. Harmony is restored.