"Completion_heads_engraver" omits measures and stems

I’m trying to use “\shiftDurations” to make a modern-style edition of some 15th century music. The duration changes are correct, but the Completion_heads_engraver is having trouble rendering the result.

There appear to be two issues:

* stems missing from tied-to notes.
* a \breve that needs to be tied as minim-semibreve-minim in 4/4 fails to draw the bar containing the semibreve, and overprints the first minim (which is also missing its stem).

I have attached a minimum example (test-minimum.ly), a PDF showing original, desired, and actual output, and a source file (test.ly) for generating the PDF.

The minimum problem demonstration:
=====
\version "2.24.4"

music = \relative c' {
d1 f2. g4
a b c2. b4 a1
g2 a\breve
r2 a2
}

\score {
\new Staff \with {
\remove "Note_heads_engraver"
\consists "Completion_heads_engraver"
\remove "Rest_engraver"
\consists "Completion_rest_engraver"
}
{
\time 4/4
\shiftDurations #1 #0 { \music }
}
}
=====

Thanks for taking a look,
Marcus

Marcus Redivo
<[email protected]>
1520 Lands End Rd, North Saanich, BC V8L 5L5
1-250-655-9238