Bug Terrain Tools 4.0.0-pre.2 BaseBrushUIGroup added controls OnInspectorGUI not called

As the title says, when inheriting from BaseBrushUIGroup and using AddController(), the OnInspectorGUI function in the controller that is added is never called. All other functions i.e. OnEnter/ExitToolMode, OnPaint, OnSceneGUI, and AppendBrushInfo are all called correctly.

Is there a reason for this? We can override the BaseBrushUIGroup's OnInspectorGUI but it would be nice if it was handled the same ways as the other functions.