Direct selection tool not selecting 3d object parts after clicking Expand Appearance

I've been trying to figure out an issue unsuccessfully where I want to color the sides/inner 3d components of objects like in the video. Here are the steps I've taken:

1. Make 2d version

2. Apply Extrude & Bevel and select depth & isometric direction

3. Apply Expand Appearance

Expected behavior is to be able to hover over and select individual 3d parts to edit: 

Actual behavior is it selects whole object and doesn't allow any editing of individual parts. 

When I mouseover the object after Expand appearance, it doesn't highlight nor allow me to select the component parts, even though I am using the Direct selection tool. I have tried clicking into the object before and after expanding, and the most it allows me to do is go into isolated editing of each part in its 2d version, and then exit back to 3d mode.

But it doesn't allow me to just select one 3d side, it just highlights the whole object as one selection.

I'm using Illustrator v 26.5, downloaded a week ago from the official site.

Would appreciate any help, thanks!!