This problem still has its place in 4.10. It looks like affecting only game modes that are specified as default ones. When you move the game mode that is specified as “Default Mode” in “Maps & Modes” project settings menu tab into another folder, the project settings reset it in drop down menu and you should simply re-select default Game Mode. I see some logic in this behavior and can’t name it a “Problem”, just a thing that must be taken into consideration 