I don’t really have an answer for you, except that I have the same strange symptoms ... excess mucus (phlegm) that is produced solely in my upper right lobe (so you aren’t entirely alone here). I’ve had so many tests (high-res CT scan last week) and they’ve all produced “normal” results. Dr.’s remain adamant that I have persistent asthma affecting that lobe despite my push for further investigations. It’s been a drag on my quality of life ... but it does seem to be getting better, slowly and gradually.