Expanded vector parameters in Material Layer instance properties stay greyed out when override enabled

This only seems to happen when the vector parameter is expanded, not when it's collapsed. Collapsing and re-expanding the parameter seems to clear the issue as well.

The material seems to use the override value when the checkbox is checked, too.

[Image Removed]

1. Create three material layers with at least one vector parameter
2. Create a couple of material layer blends, with a variety of parameters (direction, intensity, etc.)
3. Create a simple layered material, and create an instance of that. Add your layers and blends.
4. In the Layer parameters view, expand the vector parameters of your layers
5. Click the "override" checkbox to enable override
6. Observe the parameters values greyed out

Alternately, see attached project for repro. Open M_MyLayeredMaterial_inst and expand the vector parameters of