I see this issue from time to time in Civil 3d. A surface is created, but when updating the feature lines, it isn’t always represented in the surface.
The issue is usually too many edits in the file. It makes it difficult to see what the feature lines are doing to the surface, meaning people can update the feature lines, but those changes are not reflected in the surface.
In the video linked below, I have demonstrated this, along with a couple other surface best practices.
I also demonstrate a dynamo script I use for surface analysis. If you would like to try it out, it can be downloaded here: https://drive.google.com/file/d/1LYvBJEzruKHih1CVQujeb34ZtU0bJlen/view?usp=drive_link