If I add a new game manually - the platform is not filled with the one I selected (it is empty). I think it would be nice to copy the platform which you have already selected.
This also solves the problem: when I add my very first game of a platform - and that game doesn’t exist in the Core - I have to add it manually. But I can’t select the platform in the drop down - because there are no other entries yet. (easy workaround is to add one from the core first - I know).