In the attached corner cupboard It is a square corner front with an applied Chamfer in the part editor.
To rebuild the top shelf I am in the main screen.
Highlight cabinet, green hash top shelf.
right mouse click
Select remove part editor cuts
select , from selected part.
It rebuilds the shelf.
Highlight the cabinet, and for me the top shelf is unresponsive.
The other pieces in the cabinet can have the blue attachment dot but not the top shelf.
Green hash the top again.
Go to the part editor. do nothing.
exit to main.
The shelf has now regained its responsiveness



