For anyone who’s going to have this problem, here’s how I solved:
- Go to Project Settings → Map and Modes
- Check the Editor Startup Map: I suppose you have your faulty map selected here.
- Click on it and select a default UE4 map (e.g. “StarterMap”)
- Close the settings, save (ctrl+s) and close UE4.
- Open UE4 again
- Follow all the previous steps again but this time, in the step 3, choose your map!