I am new to making corridors and surfaces. I am not sure what is wrong with this surface/corridor, there are parts around the edges that are just cut out of the surface.
Try creating the corridor surface from Feature Lines instead of Links.
I have it set to read the feature lines of channels then daylight to the existing surface. I thought that might be the problem after reading your comment but the existing and proposed do not overlap the way it shows in the corridor.
I think your EG surface is created from points using a cross sectional survey.
If so my advice is to add additional data to the surface where your problems appear. You can do it from the edit surface option on the ribbon.
Can't find what you're looking for? Ask the community or share your knowledge.