Live TV Guide not an option on TV box

I just signed up for live TV. I had an exisiting Flex box that I wasn't using (the free one). We were Internet only. I was told I could use the existing flex box (which is now called a "tv box" and not "Flex" any more now that it's a paid box) to access live tv with a non-smart tv. And I'm now being charged $5/month for the privilege.

I have restarted the modem and refreshed the tv box through the app and manually by pulling the plug. All I get when I hit the "Xfinity" button is the same "Trending Live TV" that I got when I was just an Internet subscriber. When I hit the "Guide" button I see an "On now" and "Up Next" headers at the top, but below that are just suggestions for "Popular", "TV", etc. but no channel lineup.

How do I get the channel guide?