Hi all, I came on here looking for a fix a week ago for the same issue on my android phone but had no luck. After a few days I tried whatever I could to get it working again and I finally found a way that worked for me. Not sure if it will help you guys but its worth a try. Go to phone settings > apps > Now tv > storage > clear cache, clear data then force stop. This worked for me so I hope it works for you.
Now TV is very poor. There has been a bug on android for 2 years and is still not fixed. The only way I managed to get the app to work for a short time was to factory reset my phone. The issue came back after a few uses. I am not doing that again! Effectively, I am not getting the full service as I can only watch via my TV as Android doesn't work and Chromebook is not supported. Very disappointed.