Mixer dropdowns will not open under Wayland

Issue type

UI/UX bug

Description with steps to reproduce

1. Run MuseScore in the terminal with env QT_QPA_PLATFORM=wayland /full/path/to/ms4appimage, or create a .desktop file with Exec=env QT_QPA_PLATFORM=wayland /full/path/to/ms4appimage and run it
2. Open a score
3. Open the mixer
4. Try to change the soundfont or audio plugin, for example.

It just refuses to open for me. It does work on X11, however.

Supporting files, videos and screenshots

https://github.com/user-attachments/assets/cb8cfd49-60d9-434f-8c3d-4a41034b0a78

diagnostics.zip

What is the latest version of MuseScore Studio where this issue is present?

Arch.: x86_64, MuseScore Studio version (64-bit): 4.6.0-251920328, revision: github-musescore-musescore-7706108

Regression

Yes, this used to work in a previous version of MuseScore 4.x

Operating system

Kubuntu 24.04 LTS

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

Reproduce the issue by launching MuseScore with QT_QPA_PLATFORM=wayland, opening a score and then the mixer, and testing the soundfont or audio-plugin dropdowns. Compare the behavior with X11 and inspect the attached diagnostics.zip for relevant environment details. Done means the mixer dropdowns open and allow selection under Wayland without regressing X11 behavior.