Android : "You need to add at least 2 non-Android TV screenshots"

In my Developer Console for Google Play, I dragged two PNGs at 2:1 ratio (1000px x 500px) into the Graphic Assets slots for the TV and they were accepted. But I still get the message, "You need to add at least 2 non-Android TV screenshots" when I click to publish the app. So it remains in Draft mode.

I'm unsure what I should be doing differently to finalize it. I signed out then signed back in and the issue persists. I am using the Chrome browser. This app was uploaded in Alpha Testing, if that matters.