NPC Button-Mode can not interact with Gamepad

I want to use summoned NPC for a Adventure Map.

In Advanced NPC Settings, i can select all Buttons with the Gamepad, but not the

Button Mode -Control to add Buttons in the Dialog

 

When i join with the Win 10 Edition in this World, i can activate the Setting with the Mouse  and can then complete interact Controls in XBOX ONE with Gamepad. So i think it's a Bug or forget to implementation to play with Gamepad. I dont know when i play with Gamepad, has same problem in Win 10 Edition.