I'm getting audio syncing issues when opening a large MP4 file in Vegas Pro 15 Edit (build 321). The early portion of the video (the first hour or so) is fine, but near the end I get a consistent desync of a few seconds - it's very, very noticeable.

I work for a small video production company, my boss also uses Vegas Pro 15 Edit (but he's running build 261) and the exact same file opens up perfectly fine on his version of the software, with no desync at all, so we know it's not just the base file that is messed up. We've tried opening other similar files on my computer, and they are also running fine. Before I upgraded to 15, we had some issues moving files from Vegas 14 to Vegas 15, where the file we moved would become desynced in 15. We figured upgrading to the same edition of the software on both machines would fix the issue, but that's clearly not the case.

So we can't reproduce the issue consistently but it does happen regularly enough that it really is a problem for us.

Does anyone know what causes audio desync in Vegas 15? Do we need to be running the same exact build? Mine is more recent (build 321) but my boss's (build 261) is the one that is working fine - can I roll back to a previous build? Could this have anything to do with our respective computer specs?

Thanks!
Claire