Thanks for the report. What I think is happening is that the sample rate initialize to something different than 44.1KHz, and this messes with some parts of the sound engine or the renderer. It’s quite difficult for me to debug, as I can’t reproduce this issue on my machines.
Is the tempo also different when you export, or only the pitch is affected?
By any chance, would you be able to share both the exported .json and .mp3 files of a track you made, so I can have a look?