There is something weird with decode and digital channels. When I press digital when decode is active then decode is de-activated. But the other way around is different. If I press decode with digital active both decode and digital are active. Like I wrote before: this area seems to be work in progress.
It works either way for me. But the menu buttons for the extra Vertical set of controls (Ref / Math / Digital / Decode) don't function uniformly. Some of them turn on both the display of the feature plus it's menu (like Digital), but others turn on just the menu (Decode), but you still have to enable the Decode bus display with a menu selection. Plus, the light for the Decode button seems to operate incorrectly:
Start with both things off (and all button lights unlit).
Press Decode
Select Display On from the screen menu
The decode bus will be displayed
Press Digital
The digital channels will be displayed
The button light for Decode will go off - but the decode bus is still enabled and displayed on the screen
Press Decode again
The button lights again and you go back to the Decode menu.
Select Display Off from the screen menu.
The decode bus will disappear from the screen - but the button remains lit - until you turn off Digital (or turn Math on and off).