It seems if you don’t explicitly set the resolution in the game.project file the layout selection during bundle will not be used. In your case you should be able to just input 960 for width (even if that is the default value).
I have added an issue for this, hope to be able to fix it until next release: DEF-3395
The fix will be released in a few weeks. In the meantime, please explicitly set width and height in game.project instead of leaving the default values.