Audio Mixdown phase issues

Hi All,

I have had to reopen a series of films for a client to add some new VO.

The workflow has been cut in PP then export multitrack session to Audition. The issue is that the timing of the film has changed and the simplest solution is to reexport the mixdown from Audition, minus the music track and lay it back to Premier & then add the new VO clip, shunt the music back to time & make all the changes there.

The issue I have is that when rexporting the mix, there seems to be an echo/delay being added to the track, yet the audio is spot on on in Audiiton. When I open the mixdown I am hearing this delay.  Feels alsmost as if the stereo track is out of phase or something. I have tried exporting at different bit rates and all the rest of it. I have tried a mono send etc.

Needless to say the mix down worked when I did it for the original version of the film, so what is going on?

Clip attached.

Thanks for any help.