Blueprint: Menu not showing

I’m having the exact same problem. I tried replicating how they handled menus in Multiplayer Shootout, hoping I could fix the bug, but still no luck.
At the moment my workaround is just to bring up the main menu over the existing level (instead of loading the menu level). This works, but has the drawback that the server is still open until the game is quit altogether or a new map is hosted.