All my MP3/WAV/Audio exports "break-up" when using external vsts
Requires East West Opus and any virtual instrument associated with it. I'm using the EW Platinum Bösendorfer 290.
This could be an external issue however playback within Musescore 4 is absolutely fine. It lags, crackles, breaks up when exporting the audio with the Vst rather than the in-built sounds.