A materialdef of a custom material that is not in use shows default values

Import aluminium.material to project. Create new material and set the shader to aluminium. Change some property on the material, e.g. baked shadow map to another map. Save the presentation and check the values you changed -> They are now showing defaults. Adjusting any value will immediately show the correct values on all properties.

Same issue when importing a materialdef to project or after loading the project, all non-used custom materials will initially show default property values.

This may be related to QT3DS-2685.