I have just started setting up a character scene and I added a MeshInstance parented to a Skeleton node just so I would have a visual indication while writing the script. However, when the MeshInstance is parented to the Skeleton node, it is invisible. By making the MeshInstance a sibling of the skeleton it displays fine.
I have been checking the setup against the 3D Platformer Demo and the node structure and properties are exactly the same, yet it doesn't render in my project but does in the demo.
I've attached images to show what I mean.