Match Source (Rewrap) exporting incorrect audio settings

Hi,

We're having an issue in AME when selecting "Match Source (Rewrap)" as it sets the audio export settings to stereo, 16-bit as default despite the source file actually having 4 discrete channels with 24 bit audio. 

The source file is ProRes 422 HQ. We pulled the file into Media Encoder so that we could trim the file and we wanted the export to match the source settings hence why "Match Source (Rewrap)" was selected.

Do you know what could be causing this? 

We have a workaround in place but the Match Source (Rewrap) should be reliable in matching the source settings. 

Thanks