Ah! The problem is that you created the buttons yourself, having them call Switch(...). The recommended method is to write "set=Zebra-Queen" instead of "set=1" (etc.). Then the Diagram would have created the buttons by itself.
The difference is that the automatically created buttons call Twitch() instead of Switch(). And that is the routine that invalidates any existing piece values.
Ah! The problem is that you created the buttons yourself, having them call Switch(...). The recommended method is to write "set=Zebra-Queen" instead of "set=1" (etc.). Then the Diagram would have created the buttons by itself.
The difference is that the automatically created buttons call Twitch() instead of Switch(). And that is the routine that invalidates any existing piece values.