A question about grace notes

[Andrew Bernard]

I have used this construct successfully for a long time to put grace
notes before the barline:

%--------------------------
\version "2.21.3"
{
  \time 2/4
  c'4 c'
  \grace {
    \bar ""
    c'8 _~
    \bar "|"
  } |
  c'4 c' |
}

%--------------------------

In 2.21.3 this no longer appears to work in the context of my 300 page
score, whereas it used to. I am at a loss to know how to provide an
MWE as I can't make a small example where this problem arises. As this
is a large score, I have only just uncovered the matter, and it may
well have started going wrong with earlier development releases - I
can't be sure.

Hence the question is, has anybody seen such an issue with grace
notes? I wonder where it could be going wrong.

I am not asking people to solve this by editing an MWE for me. I am
asking if this is a known issue, to see if it is not something I have
been doing incorrectly all along, or something has changed recently.

Andrew