Reimporting skeletal mesh doesn't automatically create new materials

Say I import a new skeletal mesh with 4 materials. On the import settings I check Import materials. When it’s imported all 4 materials automatically get created and added to their respective material slots.

If I add more materials to the mesh and reimport it, the new material slots get added but the corresponding materials
don’t get created.

After being imported, there doesn’t appear to be any import materials checkbox in the Import settings for any given skeletal or static mesh. I’m assuming checkbox is getting unchecked.

Would be a feature request? Or is there a special checkbox hidden somewhere?

Thanks in advance for any help.