>> I am typesetting a piece and the stem in the first e quarter note
>> disappears when I add \slurUp upper notes. Is this a bug?
>
> This is the default behaviour of LilyPond: unify stems. What you need
> to do is to tell LilyPond not to use `\voiceOne` (up) and `\voiceTwo`
> (down) but rather `\voiceTwo` (down) and `\voiceFour` (down).
I think I've misunderstood what you want to do. See code below: You
should use a `\relative` block to enclose everything and `\voiceXXX`
inside to select the voice you need.
Werner
```
\version "2.24.2"
\new PianoStaff <<
\new Staff <<
\time 4/4
\key a \major
\new Voice \relative c' {
\voiceOne
e4-1\mf( a8.-3 b16 gis4) r8 \slurUp a-3
}
\new Voice \relative c' {
\voiceTwo
e2 e
}
>>
>>
```
