Using Home Designer Pro 2021: Checked default wall styles and it shows the interior wall correctly in the dialog, but the 3D view displays the exterior wall. Saved the plan file outside of HD and reinstalled HD, but no change. Re-opened the plan file; no change. Tried replacing the application support files on my Mac; still no change. Any changes made to the interior wall reflect back into the exterior, so there is no separation between the two sides. Seems that the plan is corrupt. Was able to change the interior wall through the Room Specification dialog, but need a global fix as there are many rooms. Thanks for any guidance.