The return filler (shadow that is installed flush with the face of the cabinets) needs its own global.

As it stands at the moment whenever you select the return filler (or same problem applies to an Applied End that is flush with the face of the carcase) the door reveal automatically looks at the Inset door reveal which means a 3mm gap is incorrectly added

G!Return_Filler_Door_Reveal or something like that would solve this issue and could also be used for the applied ends.

Ideally when an applied end that is flush with the face of the cabinet is added the door reveal on this side needs to automatically add -M!Applied_End_Thickness to it as the door would typically cover this applied end.