Pixhawk internal compass on 4.0 not working?

Recently I started working on my new rover build and purchased a new Pixhawk through amazon as well as a gps unit with built in compass. The problem I have is that the internal compass is not found in mission planner on version 4.0.0(official). If I re-flash the pixhawk to an earlier version 3.5, the internal compass shows up, is there something I am missing or is there something else I need to do?