After joining Now Tv recently I was disappointed to find that the mobile app wasn't working with the chromecast I have in my lounge. The cast button was on the app and it would connect to the chromecast. The Now Tv screen would show but when I pressed play on a programme it would show up briefly for a second and then the loading icon would just spin on the app and the show wouldn't play. All the other apps I have like netflix, youtube, googleplay were working so I believed the problem was with the Now Tv app.
After checking these forums I tried some solutions posted. Here's what i did:
After seeing a post about BT homehubs and the safe setup setting ( I'm with BT but have my own netgear router) I thought I'd better check my router settings. Everything seemed ok but the firmware did need updating. I updated the firmware but the problem still persisted with the chromecast.
Other posts were recommending to re-install the Now Tv app and reboot the chromecast. I did this and still the same problem.
Also posts were saying you should plug the chromecast power into the mains and not use the USB power from your TV. I did and the problem was still there.
I have another chromecast in the bedroom and I checked to see if it worked in there. It did work and the only difference I could see with the setup was that the bedroom one wasn't directly plugged into the TV but into a HDMI switch. So I tried a switch for the lounge chromecast and it still didn't work.
I had run out of ideas so the only thing left to do was factory reset the chromecast.
This worked and it's now working fine.
Here's how to factory reset your chromecast:
Go to the google Home app on your phone/tablet
If its not already showing your chromecast press the icon on the top right
This should show your devices
Find your chromecast and press the 3 dots and go into settings
Press the 3 dots top right and press factory reset
Make sure you have your WIFI password handy
I don't if it was just the factory reset that fixed it or 1 or more of the steps above with the reset.
TL;DR A factory reset of the chromecast worked for me!