Corruption when deleting a time signature after a local time signature

Issue type

Opening/saving issue

Description with steps to reproduce

1. Create empty score with two instruments (e.g. flute and piano)
2. Add 12/8 local time signature for the flute in measure 3
3. Add 3/2 time signature for both instruments in measure 4
4. Add quarter note for the flute in measure 5
5. Delete 3/2 time signature
6. Try to save the file ("This score has become corrupted and contains errors" dialog will appear)

This issue is present in all versions of Musescore 4 (I couldn't reproduce in 3.6.2)

Supporting files, videos and screenshots

https://github.com/user-attachments/assets/d340d6b5-3702-4d43-86ff-b5c4f4036390

In which versions of MuseScore Studio is this issue present?

MuseScore Studio version (64-bit): 4.7.0-260203034, revision: github-musescore-musescore-4cf0855

Regression

Yes, this used to work in MuseScore 3.x and now is broken

Operating system

windows 10

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 listed score-editing sequence in MuseScore 4, then save the score and inspect the corruption errors reported by the dialog. Compare the same sequence with MuseScore 3.6.2 to isolate the regression; done means deleting the shared 3/2 signature no longer leaves the score corrupted and the file saves successfully.