Please include a valid description of your issue to expedite matters.
1. Have you updated Premiere Elements 13 and Elements Organizer 13 to 13.1 using an opened project's Help Menu/Updates?
2. Where are you creating this slideshow - exclusively in the Premiere Elements 13/13.1 Editor or in the Elements Organizer 13/13.1 Create/Slideshow/Slideshow Builder?
3. How are you publishing this slideshow....
a. Are you referring to no sound in the 720 p or 1080p AVCHD.mp4 export file from the Slideshow Builder?
b. Are you referring to a burn to disc in the Editor using the 720p or 1080p AVCHD.mp4 slideshow as source media?
c. Are you referring to the work done exclusively in the Editor and no sound in the export to file or burn to disc of that TImeline?
What are the properties of the missing sound, and what are you using for the playback? What audio is missing...
b. just soundtrack
c. just narration
d. sound from numbered Audio Tracks?
The answers are in the details. We can decide what next based on the details in your reply.