I posted about this like a month ago and got no response. It has made my life hell on this job I'm doing. What happens is when you make the OMF PP is taking the entire audio track that is attached to every clip in your video instead of pairing it down with handles so the OMF is huge. Apparently OMF's can't be over 2 gigs with media embedded. The only work around is to render and replace but then your audio engineer doesn't have handles. (You'd think they'd at least give you handle options on render and replace.) I never ever would have started this edit of 10 different videos using the multi track functions in premiere as they obviously haven't thought through the work flow. You can't even match your audio back to original source to try and replace just the audio portions of clips in your timeline. Absolutely pathetic.
I got no response either. Yes, the work around is silly. Even in the new CC, they didn't get it all figured out. I agree, Adobe needs to think through the entire workflow for multicam editing, not just syncing cameras.
Can you upload a screenshot of your timeline so I can see how you have it set up? I can then make recommendations on how you can prepare it for OMF.
Can you define "multitrack audio file"?