Import STL mesh, mesh container: Mesh failed to load

Hi all, I am pretty new to Grasshopper and I am struggling with what should be a simple task.

I have imported a primitive mesh, created with Autodesk MeskMixer, into Rhino. Rhino has created 1 block instance for this mesh, when trying to assign the imported mesh to a Mesh Container in grasshopper I get the following error: Mesh ID xxx Failed to load.

Can anyone help?

The example mesh I am trying to use is a closed mesh, a primitive sphere saved as an ASCII STL as a test, I have also tried obj, ply file formats. Ideally I would like to assigned an open mesh, created with DAVID Laser Scanner, but I figured I better start simple. Meshes created with Rhino work just fine. I noticed that these Meshes are not Block instances but rather a mesh (when selected via Rhino).

My *.gh file only consists of a few containers such as surface, brep and a mesh.


Thank you

David