Silly question - YOU ADDED A CAMERA, RIGHT???
the blue highlight is not related - it just how the window looks.
copy paste the frame or drag it into the comment box. make sure the timeline and composition are visible. Type UU so we can see the properties.
I shouldn't have to add a camera—the default is still considered the Active Camera, right?
BUT, I did go back and try adding a camera, but the net result was the same. I tried Orienting the parent null, thinking that might be part of the problem. Nothing I did could get it to face forward.
Why is the blue ring appearing next to "Off" not related?
you need to add a Camera to make it work. the layers need a camera to orient to. default camera is an "invisible camera" and the "active camera" and you are correct in suggesting this should probably work without actually adding one but this is how it is programmed. then again Orient towards Camera and not put an actual Camera is more confusing.
the blue ring is always there. why? I don't know but it's not related to your problem. some adobe programmer thought that's how it should behave. it just sits there.
let's go over this again and make sure you do this step by step:
1. you have planets that are in 3D and their auto orientation is set to Orient Toward Camera
2. the planets are parented to a 3D Null that is Centered in the middle
3. you rotate the Null on any of the Rotation axis and the planets are.... Discs? meaning they don't face the camera straight as they rotate
I can use the insert image with no problem. maybe it something in your browser.