Can't edit animation clips after adding to timeline

I've literally spent all day on this and Googled every possible combination. This is my wit's end.

I'm trying to build up a timeline full of animations created with Unity's built-in Animation panel.

Here's one of the workflows I've been trying, but all of them seem to end at the same place, with a bunch of animation clips that are no longer practically editable ("Add Property" button in Animation panel is greyed-out).

Steps:
1) Add cube
2) Add main timeline on empty GameObject
3) Add animation track to main timeline
4) Assign cube to slot in newly-created animation track
5) Click on cube
6) Create animation clip for cube
7) In animation clip, add some keyframes and play with some transform values
8) Click on main timeline again
9) Add animation clip that was just created to the animation track created in step 3
10) Now adding additional properties in that clip is impossible

Is this just a bonkers limitation of the Unity Timeline and Animation system? If so, how do people use this thing?

 

I believe this was caused by me double-clicking on the clips from the main timeline and having that view "locked" in the animation window, and so the panel view wasn't updated when I selected the object. Unity UX researchers take note!