I tried to add a panel meter to the library.
The PCB symbol includes a rectangular outline with rounded corners:-
I added a new entry in the 3D View library with Package Style set to 'Shape'. The preview looks as expected:-
However the resulting 3D View does not work - you only get a flat 2D outline:-
If I change the Package Style to 'Box' then it works (except there are no rounded corners of course):-
This has to be a bug.