At some point the key signature disappeared on the voice part of a voice/piano score. The part is still written in the intended key. If I try to add the key sig. nothing happens. When I experimented with changing the k/s in that part to something else, the other staves changed, but the voice part one was still invisible.
So I assume that there’s a switch somewhere to hide a k/s, but I can’t find it. Sorry if it’s obvious…