Hi, The MWE …
%%%%%% \version "2.22.2" \include "english.ly" vOne = \relative { c''1\> c1\! c1 \bar "||" c1 c1 c1 } vTwo = \relative { e'1\> R1\! R1 e1 R1 R1 } \score { << \new Staff \vOne \new Staff \vTwo \new Staff \partCombine #'(0 . 0) \vOne \vTwo >> \layout { } } %%%%%% mm 1- 3 and 3-6 are note-identical. The only difference is the decrescendo in m. 1, terminated in m. 2. I believe the terminating decrescendo in vTwo/m. 2 causes the partCombine code to think there's music in vTwo/m. 2 -- I could be wrong, but the result is wrong nevertheless. Is this a known issue? thanks