Re: bug report

> % \time 1/4 in left and right hand: 1/4 before and after the grace
> % notes.
> % \time 1/4 only in the right hand: 4/4 before the grace notes, 1/4
> % after the grace notes.
> % \time 1/4 only in the left hand: ok, 1/4 before the grace notes.

(The current LilyPond version is 2.26, but this doesn't matter for
your problem.)

Before submitting a bug report please always check the Notation
Reference!  You've hit the infamous issue #34, see the 'Known issues
and warnings' section in

  https://lilypond.org/doc/v2.26/Documentation/notation/special-rhythmic-concerns.html#grace-notes

The solution, as shown in the manual, is to synchronize grace notes.

```
rh = \relative c'' {
  \time 1/4
  \grace {s8} c4
}

lh = \relative c' {
  \time 1/4
  \grace {c16 d} c4
}
```


    Werner