I have a problem with some step file from a supplier. It looks like a stretching shadow that I can 't adjust because the material removal function doesn't see a surface so it doesn't work.
The spikes in this image are not supposed to be there.
repair with the tool provided for it. Sometimes there are export or import errors.
Right-click on Surface or Solid on the left in feature manager. Then "Import diagnosis". Delete the face(s) in question until there are no more errors.