Most likely basic stuff, but never had this issue before.
Here's my workflow (really basic stuff here...)
FCP>Export QT reference>Compressor(dvd best, 90 min, ac3)>DVD Studio Pro (simple dvd)
I finished editing a short highlight reel in FCP6, and authored the dvd in Studio Pro. Plays fine on my computer (of course) but only plays in R channel on multiple televisions. No pan in FCP audio or anything weird. I did however use music exported (aiff) from Garageband, and do have 4 or 5 layers of audio mixed in, but all are set properly, and are fine. Not really sure, I have been at this for nearly a decade, and never have run into this. Maybe I'm overlooking something simple.
Any suggestions would be appreciated, and think about it so everyone could get their minds off of FCPX...;)