Apple TV+ app on my desktop will not let me sign in

All of a sudden this week I am unable to sign in to AppleTV+. I watch it regularly on my desktop. When I checked the account in i-tunes, it's there and paid. Nothing I click on responds, including the "Trial" button. I added ATV to my "allow popups" settings, and it still is not working. I've shut down and rebooted several times.