Download the licensee assets here - [Link Removed]
Place the folder "QualitySwitch" in the content folder of a project and open TST_QualitySwitch.umap
The left hand sphere will be a bold colour, the right hand one will be black. Go to the settings icon at the top -> Material Quality Level and change it, the colour of the left sphere will change, but the right one remains black.
For comparison, open the material of the top layer (ML_TST_QualitySwitch.uasset) and disconnect the quality switch from the emissive color in the SetMaterialAttributes node, and replace it with one of the 4 colours directly (i.e. circumvent the Quality Switch). The right sphere will now have the specified colour.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-119314 in the post.