Video below illustrates the issue. If WeldConstraints are being rendered, occluded highlights will always be visible, even when their DepthMode is set to Occluded. This makes certain Highlight-related features very troublesome to test in studio.
In the video you can see me toggling the rendering of welds in the RibbonBar. When the rendering is turned off the Highlight acts properly. When it is turned on the highlighting breaks. When I destroy the WeldConstraint it also fixes the problem.