Presentation tab
test field -> viewer 3D
Take a new instance of test field. Choose 3D. The structure is regular. No extern faces is selected by default, but you are able to choose min/max i/j/k. Probably this always was in this way, however, when selecting some face it would be better when selected faces would appear.
Select some face. Change to inside of box. That is ok. Change to selected faces - there is no face, however earlier we selected a face and in the menu it is still selected. Ones again choose inside of box. That is ok. Now select again selected faces - we see the box from outside. Sometimes the outside box appears immediately. I don't see the rule for it.