Move pitch up/down diatonically broken with non standard key signature

Issue type

UX/Interaction bug (incorrect behaviour)

Description with steps to reproduce

1. Define a non standard key signature (e.g. Ab and Db)
2. Add a diatonic note on the staff (e.g. G)
3. Use the Alt+Shift+Up shortcut to move up diatonically.
   Expected : from G, the upper diatonic note is Ab.
   Actual: Musescore moves from G to G#
4. From that G#, move up diatonically
   Expected: B
   Actual: Musescore refuses to move up, until G# is manually corrected to Ab (Shortcut J)

This can be reproduced with different key signatures at different places of the scale.

Two issues:

1. Moving up/down diatonically does not always move diatonically
2. When reaching a non diatonic note, Moving up/down diatonically stop working, until J is pressed to return to a diatonic note

Supporting files, videos and screenshots

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

4.4.3

Regression

No.

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

No source files or tests are named. Reproduce the issue in MuseScore 4.4.3 using the Ab and Db key signature, a G note, and Alt+Shift+Up, then trace the diatonic move behavior from that shortcut. Done means moving from G to Ab and then to B, with upward and downward movement continuing correctly without pressing J.