How can I export a Materialise Magics Project as a STL file? I created a new project in Materialise Magics, added a few parts (different STLs), moved them around in certain positions and now I want to export this project into another STL, containing my recent work.

The export menu seems to be all grey, like this function is not available. Do I have to do some repairing first or something similar? Or Magics needs other software in order to export a Magics Project to a STL file?
Instead of using save project as or export click save part as, this defaults to an STL file.