FX VSTs cause MuseScore to crash on wav export

[zacjansheski]

Issue type

Crash or freeze

Description with steps to reproduce

1. Open

Untitled score (1).zip

2. remove Aux 2 FX, confirm wav export of score and parts works fine

3. Add Aux 2 FX (anything) wav export of score and parts crashes

Supporting files, videos and screenshots

2026-04-14.11-41-09.mp4

In which versions of MuseScore Studio is this issue present?

OS: Windows 11 Version 25H2 or later, Arch.: x86_64, MuseScore Studio version (64-bit): 4.7.0-260414045, revision: github-musescore-musescore-aa5b8dc

Regression

Yes, this works in the latest released version and is broken in the nightly builds

Operating system

Windows 11

Additional context

AuxWavExportCrash.zip

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]

⚠️ Possible Duplicate Issue(s)

• Crash on .wav export specific file #32955

🔗 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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[zacjansheski]

For the record, this seems to primarily have more to do with exporting score and parts.

Issue can be reproduced with FX on aux 1 channel as well (freeze at 0:45, no need to watch entire video)

2026-04-17.11-10-32.mp4