Surely this has got nothing to do with Express Mode or Full Mode, I'm baffled by the misdirection of this being presented in that context. Look.

What's happened is the surface & multi-body icons have been removed from assembly mode entirely... irrespective of whether express mode or full mode has been enabled or disabled, this is a 1 part assembly in 2019 and the browser node is a default part icon.
I intentionally left this out of my Whats New Video because when I read it, I didn't have the foggiest idea what the heck it was implying, it definitely looked like the icons had been deleted but I thought no... there's literally no logic in doing that, I'm misunderstanding this and missing the point so I'll just leave it and move on.
But no, this has really happened?
What should have happened is the correct icon should have been displayed in Express Mode... ammiright?
Asking for a business case as to why this should be reversed... isn't that like making all the ribbon icons for all the commands a big red dot and then asking the customer base to justify why they needed them in the first place?
