Improvements have been made to the mesh diagnostics tool so that 3D surface elements are properly handled.
3D surface mesh triangles that have been placed on a separate layer and made invisible were not being recognized by the 3D mesher. This led to multiple free edges causing the 3D mesher to fail.
Now the free edge diagnostic has the Restrict to visible entities option selected and in the mesh statistics, the number of invisible triangles and the number of potential free edges are reported.