Civil 3D workaround : Corridor Surface Boundary "Add automatically" option not showing although it should

So you have a corridor made of sub assemblies that should expose one or more codes for adding boundaries automatically but this option is not offered although it should.

Watch for locked layers. Assemblies, alignments, profiles, targets, superelevation views, surfaces whatever may be related to the corridor and its surface.

If all unlocked then check this.
Set boundary to Corridor extends.
Rebuild corridor and watch the Event viewer.
If there is a warning that "could not apply mask (0) to corridor due to crossing polygon" then try this.

Set Corridor frequencies to another much larger value.
Apply.
Now the option for Adding automatically should be available.
Select the desired code.
Apply and rebuild.
Reenter corridor properties and change frequencies back to the previous values. Apply and rebuild.

Add automatically is still available and everything is working fine.

Yet another workaround.
Autodesk is unintentionally training our brains to prevent failure due to aging. Or maybe our brains are about to get burned because of all this over the years searching for workarounds, tricks and things like these trying to make their software to work as expected.
We should also not neglect all those extreme feelings of frustration, surprise, anxiety, desperation and finally...triumph that comes with situations like these.