MP3 Encoding not uploading Synth Settings
I recently downloaded the recommended LAME Audio converter so I could upload my scores with their audio. It does not upload it, however, and just simply says "Sorry!"
Try 'Contact us' on the .com page.
And take a look at https://musescore.org/en/node/197716
Could it be related?
Here the conversion works, what soundfont do you use?