Tried the first render in version 2.1.3 (MacOS version on iMac)... the video and audio are perfectly in sync inside the app before rendering. After rendering the audio is later than the visual.
First half of the screen capture is inside the app where a/v are in sync, second half is rendered video where the audio is significantly delayed. I encountered the same issue with version 1 of the app and needed to use iMovie for an additional audio/visual syncing step after rendering in SeeMusic. For now I'll continue this same process.
Maybe there's a way to address this in a future update... or some setting I can change in the current version to correct the sync?