Shulker Box isn't creating a Block-Update while opening/closing it

This is actually a simple one.

When you open Shulker Boxes, they won't output any kind of Block Update, as for example normal & trapped Chests do.

How to recreate: Place a Shulker Box to an BUD-Switch/Observer, and try opening/closing it. Now repeat the same with Chests, to see that it works there.