Tablature incorrectly assigns frets for instruments with re-entrant tuning

Issue type

Engraving bug (incorrect score rendering)

Description with steps to reproduce

When entering notes on a standard notation staff linked to a tablature staff, MuseScore's fret assignment algorithm assumes strings are ordered from lowest to highest pitch. This causes incorrect fret assignments for instruments with re-entrant tuning, where one or more strings break this pattern.

Affected Instruments with re-entrant tuning:

Instrument	Tuning	Re-entrant String	Status
5-String Banjo	G4-D3-G3-B3-D4	String 5 (G4) is highest, starts at 5th fret	✅ Fixed in 3.6.2
Guitarrón Mexicano	A1-D2-G2-C3-E3-A2	String 6 (A2) lower than string 5 (E3)	❌ Bug
Ukulele (High-G)	G4-C4-E4-A4	String 4 (G) higher than string 3 (C)	❌ Bug
Charango	G4-C5-E4-A4-E5 (5 courses)	Middle course (E4) is lowest pitch	❌ Bug
Venezuelan Cuatro	A3-D4-F#4-B3	String 1 (B) lower than string 2 (F#)	❌ Bug
Timple Canario	G4-C4-E4-A4-D5	G and C are re-entrant	❌ Bug
Baroque Guitar	Various	Lower courses often tuned octave higher	❌ Bug

Note: The 5-string banjo was fixed in MuseScore 3.6.2 with special-case code that handles its unique 5th string (which starts at the 5th fret). However, other re-entrant instruments remain affected because the fix was instrument-specific rather than a general solution.

Steps to Reproduce

1. Create a new score with Ukulele (High-G tuning: G4-C4-E4-A4)
2. Add a linked tablature staff
3. Enter note C4 on the standard notation staff
4. Observe the tablature

Expected: Fret 0 on string 3 (C string) - the open C string
Actual: Fret 5 on string 4 (G string) - because the algorithm finds G4 first and calculates C4 = G4 + 5 semitones

Impact

• Pedagogical: Students learning these instruments see incorrect fingerings
• Professional engraving: Published tablature shows suboptimal or impossible positions
• Playback: While MIDI pitch is correct, visual representation misleads performers
• Affected Instruments: Many of them are central to traditional music (mariachi, Tuna, Andean, Hawaiian, Canarian, Venezuelan)

Related Discussions

MuseScore Forums

• Guitar in re-entrant tuning - Baroque guitar issues after banjo 5th string fix
• Charango tablature issues - "Program confused by re-entrant tuning"
• Theorbo tablature - Highest course is 3rd, not 1st
• TAB for ukulele hi-G tuning - G string shows only zeros
• Double C banjo tuning - Tab only allows "0" on each string
• Guitarrón and Vihuela parts - Workaround using baritone guitar

Supporting files, videos and screenshots

Files used for screenshots below

reentrant-files.zip

Current Issue: observe all notes written in first string with notes in red meaning out of range because no available frets below 0 in first string. These notes can be played on the 2nd or 3rd strings, and MuseScore should automatically choose the appropriate fret there.

Expected: the notes should be displayed across the 1st, 2nd, and 3rd strings, choosing the lowest possible fret positions.

Banjo: notes are displayed correctly in tablature

In which versions of MuseScore Studio is this issue present?

4.6.0

Regression

No.

Operating system

macOS, windows

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