GameMode is NULL after game starts

Using 4.3.0

I am unable to reference the GameMode using GetWorld()->GetAuthGameMode();
It returns a NULL address AFTER the game has started. However, it returns a proper value before the map is loaded.

The game mode is set in my DefaultEngine.ini document as follows:

[/Script/EngineSettings.GameMapsSettings]
EditorStartupMap=/Engine/Maps/Templates/Template_Default
EditorStartupMap=/Game/Maps/Example_Map
bUseSplitscreen=True
TwoPlayerSplitscreenLayout=Horizontal
ThreePlayerSplitscreenLayout=FavorTop
GameDefaultMap=/Game/Maps/Example_Map
ServerDefaultMap=/Game/Maps/Example_Map
GlobalDefaultGameMode=/Script/TimeIsUp.TimeIsUpGameMode
GlobalDefaultServerGameMode=/Script/TimeIsUp.TimeIsUpGameMode

How can I make sure the GameMode is properly set when the map is loaded?

After further investigation, it looks like the player client is also calling for the GameMode which will result in NULL.

GetWorld()->GetAuthGameMode();

Where did you call?

GameMode is only valid on the server. Are you calling this on the client?