My list on Apple TV+

Do you pay to subscribe to Apple TV+?

Check TV > Account > Account Settings from the TV app's menu. Does everything look good there?

Surely you see the red-yellow-green circles shown at the upper left. If not, click the top of the frame to exit full screen. What do you see along the top to the right of the three circles?

Yes, that’s the issue. The TV app was released by Apple with MacOS Catalina in 2019. You’re out of luck until you upgrade.

Enjoy your Apple gear.

From the Help section of the TV app:

Perhaps you need to scroll ...

You are showing the "TV+" pane of the Apple TV app.

As the help provided above explains, you must view the "Watch Now" pane to see "Up Next."

Oh, you’re viewing this using Safari!

That is the incorrect method. You must use the TV app.