Before we get too far, I just want to mention that im no expert by any means… I’m sure there are more knowledgeable people on here, but getting them to comment can be slow. THAT BEING SAID…
I think Onyx defaults all the color channels to full in the background for reasons beyond me. I have gotten around this by making a separate playback button with all color channels of all my fixtures at 0%. In the cue settings I have the “stay alive” button on. This way everything will be black while I’m programming. If you have a programmer window created, you will see that isnt a R 0% or G 0% or B 0% under color. This means you can still program correctly. Without this cue, as you’ve noticed, everything will go back to rgb white as soon as you clear out.
You’re Intensity submaster sounds like it’s working correctly, it just has the weird full color on in the background. I’m not sure if there is a way to turn this off or not. Once you make that cue and activate it, having your intensity fader at full will do nothing, but the fixtures dimmer will still be activating. You can verify this in the active cuelist window (make sure your intensity fader is selected), and it should show whatever that fixture profile is named with the intensity at 100%. Next bring up the red fader and it should turn red.
I’m hope this helps, I’m not at home to take screenshots of Onyx. I have also noticed this forum seems to be dying off. I dont use facebook, but there is also a page for Onyx. It may be more active.
EDIT
I forgot to mention the virtual dimmer is a setting you have to activate as you patch a fixture without a dedicated dimmer channel. It’s pretty useful, but as I said you will have to repatch your rgb profiles.