We’re aware of an issue at the moment where your viewing is being returned to the Chromecast main page when the ads come on during live events.
Our Team are working on this and we hope to get this resolved asap.
In the meantime if you are affected, you just need to start the stream again and the viewing should continue.
We're very sorry for the inconvenience this has caused, as soon as we have an update we'll post this on the community.
NOW TV Team