This is the response I have received:
"Thank you for your email regarding All 4.
We are sorry to read that you have been experiencing issues accessing All 4 via Now TV. We must advise that we have been made aware on an issue effecting this model. However, we have passed on your information and feedback to our engineers who are working on fixing this as soon as possible. We would like to thank you for your patience while we work on resolving this issue.
We apologise once again for any disruption this may have caused and hope you find this information useful.
If you require further information, feel free to email me back or visit www.channel4.com/4viewers/faqs
All 4 Support"
My NowTV smart box is not effect by this All 4 App glitch reported here, but i noticed that my box had a All 4 App software update this afternoon (maybe it's a bug fix software rollout ?).
Maybe go into the box or stick system settings to see if there is a All 4 software update on your nowtv devices.
Can't guarantee this new update is a fix, but no harm in giving it a try.