Same here. I've been struggling with All4 on my Now TV black box since 8th, as it crashes the app every time it opens.
I've uninstalled and reinstalled the app but no luck. I managed to get it working by pressing the arrows whilst it is launching, as it seemed to be the home page causing the error, but this has stopped working too now as the watchlist can't find the content.
I've emailed Channel 4 but not heard back after their initial email.
We just watched Countdown on All4 on a Roku Express 4K, and it was fine.
So it looks like it’s Now-specific, perhaps even Now-device-specific, but I haven’t got any Now devices hooked up that I can test.
Just had an email from Channel 4:
Thank you for this information.
We greatly appreciate you sending so much detail, as it will further our investigation greatly. We have had a couple of reports of this happening to viewers, and we sincerely apologise. We have already escalated the issue, and it is being worked on by our All 4 engineers, and they hope to resolve this soon. We have forwarded your details so they may be able to find a common trend among the reports. We appreciate your patience while we look into this for you, and will keep you updated.
We apologise once again for the disruption to your service.