When mounting machines into new Manufacturing Cells, a 'Default reference machining axis for Part Operation.1' is created. Where is this axis coming from, and how can it be changed?

This axis is often oriented in an unideal plane. When resources are mounted, they inherit this orientation, and are therefore mounted in awkward positions. Manual intervention is required to move them to the correct orientation. As you can see the axis in the photo below is in random location half-way into the machining table.