Jumps/markers duplicated in custom part

[its-not-nice]

Issue type

Engraving bug (incorrect score rendering)

Description with steps to reproduce

1. Create score with multiple instruments
2. Create some extra system markings instances
3. Add a jump/marker
4. Create a new custom part
5. Reveal the top instrument

The jumps/markers will be duplicated (equal to the number of system markings instances in the score). Doesn't seem to affect other system markings, and also doesn't happen in any pre-existing parts.

Supporting files, videos and screenshots

Screencast_20251006_103104.webm

In which versions of MuseScore Studio is this issue present?

4.5 (when this feature was introduced), 4.6, nightly (6 Oct 2025)

Regression

No.

Operating system

Any

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

[mmeyn]

Thank you for reporting this! That's what I tried to report when #30292 happened 😉