Are you talking about LOE, when they are heading up to rescue Palpatine?
It sounds all right to me, with headphones. Do you mean the center channel literally blanks out at that point?
EDIT: Yep, that seems to be what happened. I don’t have a surround setup. Was this very apparent? I don’t want to reissue just for this, but I can make a note about it in the event I ever do.