Having exactly the same issue. Validated Sports Day Pass yesterday 14:00. Worked fine until 18:30 when I stopped watching. Went to watch NFL at 21:15 & won't cast from tablet. Rebooted Chromecast. No change. Getting "Viewing Stopped" error message. All other apps casting ok. Tried customer support. They suggested reboot again. No joy. They said they will escalate issue. That's it! Extremely frustrating! Has anyone resolved this problem?
I was having the chromecast viewing stopped problem yesterday afternoon.
I could watch NOW TV on my tablet but not cast to the Chromecast.
Trawling this forum someone reported that the problem was caused by using a PC with the google chrome browser on the same home network.
My son was using Google chrome on his PC.
After closing the chrome browser I could then cast to the Chromecast.
This may have been co-incidental I have not tested it again to prove it.
This problem appears to be unique to NOW TV.
Chrome browser/Sky Now casting failure does appear to be reproducible.
Sky Now failed to cast to Chromecast from iPad, with error msg. Had Chrome browser open on Mac so quit it and retried Sky Now. Casting from iPad worked. Opened Chrome browser on Mac, Sky Now failed to cast. Closed Chrome browser and able to cast Sky Now from iPad again.
Repeated a few times with same outcome so suggests some link, at least in this case.
Mac and iPad on same Wi-Fi network.