Piano mp3 is silent when exported.

[mozbadel]

Issue type

Import/export issue

Description with steps to reproduce

For some time, I have been producing singalong files for my choir using the following technique:

1. Create .mscz file (in this case FNO 260415)
2. Export to midi file
3. Import midi file (deleting non-singing parts) to Dreamtonics Synthesizer to create the singalongs.
4. Render the singing tracks in Synthesizer to create .mp3 files for each part and the ensemble
5. Export from original Musescore file to create the full .mp3 and (on its own) the Piano accompaniment .mp3
6. Import Accompaniment .mp3 into Audacity with voice .mp3s from Synthesizer.
7. Export final singalongs with accompaniment from Audacity.

I have just made some slight changes to one of these .mscz files (I can’t remember exactly what I changed – maybe instruments in the mixer, perhaps other stuff too) and now, for some reason the .mp3 for the piano accompaniment (3.8MB) is silent, even though the full .mp3 for all parts does have the piano.

Going back to a previous version of the song (FNO 220916), the export of the piano part on its own works correctly.

I am using MacOs 26.3.1 (25D2128) on MacBook Pro, with Musescore 4.6.5.

Included in zip file: FNO 260415.mscz, FNO 260415.mp3 (which seems fine), FNO 260415-Piano.mp3 (3.8MB but silent) - and for comparison: FNO 220916.mscz, FNO 220916.mp3, FNO 220916-Piano.mp3

Supporting files, videos and screenshots

Piano mp3 bug.zip

I am using MacOs 26.3.1 (25D2128) on MacBook Pro, with Musescore 4.6.5.

In which versions of MuseScore Studio is this issue present?

I am using MacOs 26.3.1 (25D2128) on MacBook Pro, with Musescore 4.6.5.

Regression

I was unable to check

Operating system

I am using MacOs 26.3.1 (25D2128) on MacBook Pro

Additional context

No response

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible

[coderabbitai]

🔗 Related PRs

#32853 - Fixed a recursive call to the async::processMessages [merged]
#32869 - Fixed a recursive call to the async::processMessages. 4.7 [merged]

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[MarcSabatella]

The piano track is muted in piano part of the 260415 version, so it's correct that exporting the part produces silence. Open the part, unmute the piano, and then it will export with sound.

I'm assuming you don't remember muting it? There have been bugs in past versions where under circumstances, scores imported from older versions would have their parts muted. All known cases of this are fixed now but if this score was imported from MU3 in a version that still had the bug, then the part would be muted then and if you saved it in that version, it would muted when opened in later fixed versions. So maybe that is what happened?

See also #32864 and #27025