When both voices in \partcombine finish a \quoteDuring at the same time, only one voice is rendered for subsequent notes.
\version "2.18.2"
\addQuote "melody" \relative c'' {
a4 a a a
d d d d
}
\addQuote "alto" \relative c'{
f2 f
g2 g
}
\partcombine
{ \quoteDuring #"melody" s1
\quoteDuring #"melody" s1 }
{ \quoteDuring #"alto" s1
% This does not get rendered:
\quoteDuring #"alto" s1 }
If the last line is changed to notes, they are rendered but the \quoteDuring for the same measure in the first _expression_ is not. Lilypond does not throw any errors or warnings when compiling these examples. Using the << \\ >> construct does not cause this issue.
If the quote durations overlap, there is no bug:
\partcombine
{ \quoteDuring #"melody" s1
\quoteDuring #"melody" s1 }
{ \quoteDuring #"alto" s2
% No problem:
\quoteDuring #"alto" s1. }
Thanks,
Nathan