Moving or changing the name of a map that is set as the Game Default Map or Editor Startup Map does not update the map settings. These will still refer to the old name of the map, and the Editor and Game will load with a blank map instead of the intended map.
1. Launch: UE4Editor.exe (any project)
2. File > New Level
3. In Project Settings > Maps & Modes, change the Game Default Map and Editor Startup Map to the new level
4. Rename the new level
5. Close the project
6. Reopen the project
The project opens to a blank map. The Game Default Map and Editor Startup Map settings still refer to the new map's original name and has not updated to reflect the change.
Head over to the existing Questions & Answers thread and let us know what's up.