AutoCAD 3D Shell command does not work

[rfayner]

I am trying to create the Cater drawing from training session in Youtube.

https://www.youtube.com/watch?v=MVYVIJrGBy0.

On minute 3:43 they instruct to use Shell command,

As SOLIDEDIT Select a  3D Solid, select solid object, Click Add, Click Remove. Then I Click on three surfaces, next step 

Remove faces or [Undo Add All] - I click enter.

Next step SOLIDEDIT Enter the shell offset distance - I enter either 1/8" or 1/4"

Next step SOLIDEDIT [Impront seParate solids Shell clean Check Undo Exit] <eXit>

I click enter twice -Nothing happens.

Please, advise

I have included actual file I use for your reference.