I had no problem loading the correct approach from the world map. That’s not to say that this doesn’t happen. You’re right that this occasionally does happen. I was just unable to reproduce the issues in this instance.
However, another thing to keep in mind is the role of the flight crew in managing the automation in a large aircraft. The pilots need to ensure that the plane is set up for and configured for the route that they are cleared.
I suggest that you validate that the correct procedure is set up in the FMS as the approach gets assigned by the controller. Although the flying community, especially airline dispatch offices, are fairly good at requesting and predicting runway assignments in flight planning/pre-departure clearance, operational needs and weather in the national airspace do change runway assignment. We should always be ready to receive new clearance and/or validate set up.
In this case, yes, the sim probably loaded the wrong runway, but that’s something a crew would have corrected/looked at when validating the flight plan prior to push and again as the runway assignment came in on descent.
In real life, one of the biggest difficulties student pilots have when training for instrument rating is staying ahead of the plane - making sure the plane is set up to fly the route before it needs to fly the segment ahead.
Good luck! 
EDIT: I mean this only to offer some additional realism going forward, as you start to develop your own mental checklists of what to do and when.