I have seen similar questions about this on forums from years ago, but I have not seen an answer that solved this problem. Maybe someone now has a solution. I am trying to add voices to characters in my animation, and when I play the animation in the frames, the voices are in sync, but when I hit "test movie," the voices fall out of sync after the first few lines (the sound begins too early). I even tried pushing back the sound in the frames to be behind, but it does not have an equal effect at the "test movie" stage. My sound files are MP3, they are set to stream, repeat x1. I also tried adjusting the frame speed to 23.98 per second as another forum suggested. Nothing works. I spent 5 weeks on the animation just to be stopped by this issue as I was about to finish. Very frustrating. Feeling like Adobe Animate is ripping me off. Any help is appreciated. Thanks.
WAV files are a lot better for scrubbing the timeline, though I'm not sure if they would avoid the timing problem you get with MP3.
I did report the going out of sync issue not too long ago, but I can't find where my report is.
One thing you could try is to have a silence sound that occupies the full length of the timeline, and have that set to Stream. I suspect that any gaps in the audio could cause problems, and having a sound that goes from frame 1 to the end might help.
Are you going to end up exporting to video? If you were you could fix any remain sound sync issues in Premiere or Audition.
Thanks for the suggestions. I had tried the silence sound layer but it didn't help. I can try WAV files but I need a converter that offers that. Right now I am trying a work-around using Movie Maker and will see if that works.
In case this helps anyone, the silence trick did work for me.