I’ve encountered this issue today. If I have a solo player which has an ossia or an extra stave, it’s impossible to change the instrument for another one. The option is enabled, but the instrument picker doesn’t come up. Is this a known limitation? It took me a while to figure out what was causing it.
Known limitation. Create a new player, copy and paste the music manually, then delete the old player.
Thanks, @pianoleo ! That’s what I thought.