Change of RehearsalMark behaviour

[David Sumbler]

I set a piece a while ago using Lilypond 2.19.48.  It consists of 2 staves, and I used \mark for some annotations that I wanted to appear above or on barlines - mostly the "crotchet - dotted crotchet" type of thing.  Sometimes these only applied to one of the staves, so I would specify the mark in the music for the appropriate staff.  I added:

      \layout {

\context { \Score

   \remove Mark_engraver }

\context { \Staff

   \consists Mark_engraver }

      }

and it all worked just as intended.

I was recently asked to make a new version of the piece.  The main change is from a male voice to a female one, but this necessitated a few changes in the other (instrumental) staff.  I ran convert-ly on copies of the original files as I now had Lilypond 2.23.4 installed.  I then edited these to produce the new version

Unfortunately the behaviour of RehearsalMark seems to have changed.  Whereas previously a mark only appeared over the staff whose music it was specified in, I find that now all of the marks appear in both staves, regardless of which staff they are intended for.

Is this a bug or an intentional change?  And is there another way I can use marks to get the result I want and previously had?

David