[libGDX] How to hide Android titlebar when Google Play Games is initialising?

When I initialise Google Play Games, when my game has loaded, and the “connecting to Google Play Games” window appears at the start - the Android titlebar also momentarily appears. It disappears once the GPG login window disappears. How do I stop that happening? In my game’s manifest, I have the following style set within the activity tag:

android:theme="@android:style/Theme.NoTitleBar.Fullscreen"

This obviously works, as I don’t see the toolbar when my game is running. I had a look at the Google Play Game Services GameBaseUtils manifest, and it doesn’t have any activity tags, so I added the NoTitleBar style to the application tags like this:

<application
  android:theme="@android:style/Theme.NoTitleBar.Fullscreen">
  <meta-data android:name="unityplayer.ForwardNativeEventsToDalvik" android:value="true" />
</application>

However, the title bar still shows (momentarily) when the game loads and Google Play Games is initialised. Is there any way to fully get rid of the titlebar when GPG initialises?