Hi! Welcome to the forum!
Yes, this is a known issue and a really annoying one too... It occurs if the video contains 2 different audio encodings (or different channels) in one stream. This will make the converter fail on it.
Anyhow, I hopefully fixed it in the new version (v2.1). Indeed, I only added the parameter "-async 48000" to the ffmpeg profiles.
The new version is currently in betatesting and I fixed a lot of other problems too. I will release it really soon - expect it this week!
If the problem persists in the new version, it would be great if you post a bug report (see help file) here, so I could have a look at it.
Creator of MC-TVConverter