Materials not saving in Mesh Library scenes?

Question

This seems to be a recent issue as I have done this before but I may be overlooking something.

Steps taken to reproduce the issue:

1. Create a new mesh in my Mesh Library scene.
2. Apply a material to the chosen mesh in both override and mesh itself.
3. Convert to a Mesh Library.
4. Create a GridMap in main scene and plot the tile in the editor (The material appears just fine in editor)
5. Run the game and see that the material is gone and the mesh is white.

Also, when I reload the mesh library scene in the editor, the mesh is missing its material again.

What the tiles look like in-editor:

What the tiles look like in-game:

Answer 1

I figured it out! So if anyone has issues with this in the future:

Only modify the material inside the mesh itself and make all child resources of that mesh and material unique. I'm not sure if this is a bug or the way things are meant to work, but it's my workaround for now.