Assuming you don’t have boost it can take up to 10 minutes I believe for the “device” to become inactive.
From what I’ve seen across the forum other people have suggested logging out the device to watch on another. Far from ideal.
FYI that I do not work for NOW, I am simply a NOW customer trying to help I am a Community Contributor This means that I know a lot about the service and like you I am still a customer. For any account issues you’ll need to contact staff via customer support.