I think there's another bug in 3D View.
I've done as you described (all done in Demo Show V8)
Midi to DMX fixtures channels
in tab Fixtures, click on button "Menu" in the toolbar in tab Fixtures, and select "Fixtures Midi inputs"
press "learn" and move the midi slider/button (then you see the midi infos at the left side of the "learn" button)
select the priority mode with the dropbox
add an optional comment
press the button "Add / Update"
select the line in the list
check the channels to drive with the midi input
I've select HTP Mode and took "moving_light_spot_#1" and assigned Pan & Tilt.
Checked it in DMX_Bragraph. Both channels are blue marked.
Moved the assigned Midi Sliders -> Bargraph moving and a real connected Fixture too.
Gone to "Live" switched on 3D View Button and opened the 3D View Window.
But in 3D View I can't see the fixture moving!
Then I switched on a Spot light color scene and now I can see fixture moving.
Switched it off -> no moving. Switched on a Led Wall Scene -> I can see moving
To result is: I doesn't matter which Scene is switched on, only if a scene is on you can see the Head moving in 3D.
Hope you understand?