Can you provide screenshot of your inputs to the component or internalize the results and share the file? It’s hard to guess without being able to reproduce the problem. Also are you using the latest release. I remember that there was a number of similar discussions on GitHub after the previous release.
The contour mesh component has an output named underlayMesh. Check if it outputs some mesh. When the component fails to create a perfect intersection, it uses the underlying analysis mesh. If you have turned preview off for the contour mesh component and using a mesh component to visualize the mesh, then connect the output from the underlayMesh to the mesh component. That should fill the gap that you’re concerned about.
you need to connect BOTH meshes to the geometry.
If you check the underlayMesh output, it says: A mesh that is colored face-by-face (like a typical Ladybug mesh), which is plaed under the contour mesh to make the visualization read when the Rhino intersection fails to produce a complete contourMesh.