I am typesetting a musical example (for piano) that begins with a slashed grace note (unslurred) in the right hand. Judging from the result I'd say LilyPond is trying to put it in the previous bar (but I'm not an expert); either way the result is that the lower staff begins with the wrong clef and then changes it in the first bar of the example (perhaps it created a staff context for a previous bar that is not in the example in order to place the grace note in the other staff?). A tiny example is at the end of my message. At the time of writing the only workaround I can see would be to include the last beat of the previous bar (but there is no reason to do this, and my supervisor would more than likely point it out to me when he sees it). It's from an urtext score, so I have no licence to change anything. I appreciate if anyone could tell me if I'm doing something wrong.
\version "2.16"
<<
\new Staff {
\relative c' { \slashedGrace c8 c1 }
}
\new Staff {
\clef bass
\relative c { c }
}
>>