I found out what was wrong. It was actually already mentioned by Gil but I didn't think it applied to my situation because I didn't modify my dimming curves. However, I did go into them just to see what it was. I then clicked cancel on the dimming curves screen. That didn't seem to matter. It still saved blank dimming curves in the xml.
In a prior post in this topic Gil said:
Do you know what you did with the dimming curves to get it into the state it was in?
You're file looked like this:
<dimmingCurve>
<red brightness="" gamma=""/>
<green brightness="" gamma=""/>
<blue brightness="0" gamma=""/>
</dimmingCurve>
Whereas this is what it should look like by default:
<dimmingCurve>
<red brightness="0" gamma="1.0"/>
<green brightness="0" gamma="1.0"/>
<blue brightness="0" gamma="1.0"/>
</dimmingCurve>
Well Gil, I can tell you how to replicate this. In the layout, go into Models and modify a model. I've verified that it happens on a vertical matrix and an arch. Then click on dimming curves. You'll notice that the values are all blank rather than 0. Don't change anything. Remember, we're just here because we were curious as to what this feature was. Click Cancel in the dimming curves window. Click OK on your Model window and then OK on the Model List window. Finally, click Save on the Layouts window. If you go and look at your xml you'll see that the dimmingCurve element is now present (even though you clicked Cancel) and the values are blank rather than 0.
Once I removed the <dimmingCurve> element from the xml of my vertical matrix then everything worked as expected in the sequencer. I can only assume that the reason it worked when I used the group containing the vertical matrix is perhaps the group ignores the <dimmingCurve>?
Hope that helps.