Compressor V 4.7 dropping audio track t

When sharing to compressor 4.7 my project is losing audio. The audio segment is within a compound clip, with whole timeline also in a compound clip. I've detached the audio but left it within the intial compound clip. All other audio is fine. No fancy transations, just a dialouge that goes missing. Exporting from FCPX 10.7.1 and rendering to Quicktime "social platform" HD 1080P. The audio plays perfectly in the timeline (within the project compound clip - which I used to apply some minor sharpening). I've tried with a different render preset..same issue. My guess, the transiation or lower third (which comes just after audio starts), is creating a problem. It's no good to me without the Lower Third or the transition.