Hi,
There is a significant difference between UI5/6 and UI7 in this. Before the default width of a scene group was 3 button witdths, i.e. "x": "3" even if you set it to 1, 2 or 6. And if you want to make it wider, the device on the panel had to get wider as well ("x">"4" in the top definition) else the values would not be shown.
However, with the new UI7 layout, the width of the device is fixed. Now the scene group x means the number of columns you like to use and you can make it 1, 2, 3 or 15. The higher the number of columns, the narrower they get. If you now position a control in the control group mapping to that scene group you place the control relative of the number of columns. Example will help;
SceneGroup "x": "1", means you can use a value between 0 and 1 from left to right.
SceneGroup "x": "3", means left 0 -1 is first column, 1-2 is second and 2-3 is third, but still on that same left to right width.
I think the quickest and most compatible change is to SceneGroup with "id": "1" and change "x": "6" to "x": "3". I cannot test my assumption right now, but give it a shot.
Cheers Rene.