I followed this guide to implement a loading screen when using seamless travel and server traveling: Loading Screen | Unreal Engine Community Wiki.
However the FCoreUObjectDelegates::PreLoadMap.AddUObject(this, &UMyGameInstance::BeginLoadingScreen);
BeginLoadingScreen
is not called when using server travel to change from one map to another. It is called when loading into maps using “Open Level” as I navigate from the main menu to the lobby menu as well as when the game first opens.