If you are having issues spawning servers, try the following:

1. Does your command line for the server look like this? "C:\\Program Files\\Epic Games\\UE_4.24\\Engine\\Binaries\\Win64\\UE4Editor.exe" "C:\\Path\\To\\My\\Project.uproject" /Game/ThirdPersonCPP/Maps/ThirdPersonExampleMap?listen -server -log Including ?listen and the map.
2. Does the client command look like this? "C:\\Program Files\\Epic Games\\UE_4.24\\Engine\\Binaries\\Win64\\UE4Editor.exe" "C:\\Path\\To\\My\\Project.uproject" 127.0.0.1 -game -log Pro Tip: 127.0.0.1 should work on any machine.
3. Is Steam VR or Oculus stopping multiple games from loading?
4. Close the editor, delete Binaries and Intermediate folders and restart.