(Apologies for any mangled terminology; I'm an amateur when it comes to music theory stuff and all I know is half-remembered from school two decades past.)
Due to not finding a good way to split a measure in half at the end of a system (and perhaps there is a proper solution to this which would solve the problem anyway, please enlighten me if so), I ended up settling for changing the last measure of a system to 3/4 and changing the first measure of the next system to 1/4, to match the split measure of the paper copy I'm transcribing. Visually it appears the same, and the generated piano sounds correct, so I figured this was good enough.
However, for some reason the rest note in this 1/4 measure insists on showing as a whole rest instead of the quarter rest it *should* be showing as (since a 1/4 measure should only have time for a quarter rest). If I put a note in the measure it only permits at most a quarter note, and if I put something smaller than a quarter it correctly fills the remaining space with eighth rests or whatever, but when empty it refuses to show the correct quarter rest.
If I'm doing anything wrong here please let me know, but at first glance this looks like a bug.
Please see attached screenshot for details.