NullVoice and Cautionary accidentals appear to interact

[David Wright]

Hi, I'm used to a bit of work setting up lyric alignment with
NullVoice—normally involving making sure that NullVoice has the
most subdivisions of any part—but I was surprised by the appearance
of the natural sign on the B line.

As you can see, I normally copy one part (typically soprano) into
the NullVoice and then subdivide it with ties as in MYalign.
The Notation Manual recommends modifying NullVoice with the moving
part as in NMalign (but only if in the same Staff). Both methods work
with accidentals, but MYalign fails when they're cautionaries.

Cheers,
David.