Cannot move layers in the timeline

Wait!!!! It's so simple....

You have LOCKED that Group.

Select the "Null Objects" group, and choose Object->Lock to UNlock it - or just press Control-L, with that group selected.

AFAICT, it appears that "Null Objects" is the name of a group.

What exactly happens when you drag it?

The Spin behavior is applied to the Earth object, which is NOT part of the group.

If you want it to be together in the same group, either make a new group encompassing all, or use the Layers list to put Earth inside the group.

If I am misunderstanding (which is quite possible!), please elaborate.

You can also click on the lock icon in the layer list or timeline to unlock layer items. You probably just need to unlock the group, when that is locked it locks all layers inside.

Can you tell us these "null objects" came to be in your project?

I looked up the concept and it appears that this is something that is not supposed to exist explicitly in Motion (but is used in After Effects).

I also only just noticed that there are diagonal lines crossing this "null object" thing.

I was under the impression that this was just a group that you had named "null objects" - or is this something else entirely?

What do you see in the layers list?

Would it be possible to export XML of that project and share that XML file so we can look into the structure of the project?