HDCAM SR Edit to tape issues no audio

I'm editing to tape with FCP 7 through a MATROX to HDCAM SR tape with the SONY SRW-5500 deck.
The first Assemble always goes off without a hitch but if we find an issue and need to do an insert onto the tape with audio the picture will insert but there will be no sound.
The only fix is to re black the tape and start from scratch. I've tried 3 different Matrox MX02 LEs, 2 different SR decks, and 4 different MAC Pros.

Also this will never happen when I'm laying off to HDCAM with 4 channels of audio its only when I try to insert onto an HDCAM SR with 9 tracks of audio.

Anyone else deal with this madness?
Im stuck.

Thanks
Chris