Ha. Well I guess I didn’t pay attention and the forum parsers parsed my xml. In the mean time, I solved my issue. I was writing markers with RGB values 127,127,255 and they should have been 127,0,255. I guess I was creating an invalid marker color for FCP and thus it was invisible.
It always seems to require making a forum post before you can step back and see your mistake right in front of your nose!