Hi and welcome!
Please post a debug log as described in the help file so I can see what is maybe causing the sync issue. You can try to set a start and end time for conversion (maybe 1 min.) to cut the stream a bit which maybe fixes the issue.
This behaviour I often experienced on streams that contain multiple audio codes. For example if you watch a movie in surround followed by a commercial in stereo and then again a movie in surround.
You can only really fix it by demuxing the stream, and manually cutting the stream in a video editor software - but that's another story...
I'm completely rewriting the audio handling for the next version. If you don't want to demux and cut the file, you could wait and see if the next version fixes it for you. But it's never wrong if you post a debug log for me...
