PowerPoint issue

I have made a PowerPoint file that consists of 32 photographs and an MP3 audio file of a song. I want to load a video file of the PPT file onto YouTube.

I have converted the file to MP4 format but when I run it the audio file has become corrupted. It runs fine over most of its five minutes but the sound is disjointed in a couple of places.

Help much appreciated. I am using Windows 10 and Office 365. The PPT and MP3 files are attached.