I’ve got a piano part where I want middle C to generally be played with the left hand. So I set the split staff (not poly) point to C#3 and that works great. However there is one spot where a single C3 note should be played with the right hand not the left. How do I get it into the upper staff? When I right click on the note there is an option to display the note in the upper staff. However when I do that it still keeps the note as part of a chord in the lower staff, just with the top note way up beneath the upper staff. This is also messing up the left hand notation in the lower staff. It should be a whole note chord, but it displays as dotted half notes tied to quarter notes to accommodate the misplaced C3 quarter-note. 
Thanks. That solved it. I was under the miss-impression that polyphonic was for stuff like vocal harmonies and split was for keyboards.
Interesting that two of us were posing the same question at the same time.
Yeah, using just 2 of the 8 voices of the polyphonic staves is a workaround.
Cool, Thanks for this info. I run with this and soon have a piano score! (Great minds think alike!) 