It is because of that update directly because of that update. The reason why yours still works if indeed it still does is that you haven't signed out and tried to sign back in. I got mine working using my solution but had to change my password. I did that but didn't change the password on my PC and it signed in fine using the old password...it's shouldn't do that, it's a big mess of an app and a disappointment.
From what I gather the Now TV app will be decommissioned. So the best and only way will be to download the Now TV player