[Bug] hide empty staff & chords between staves

hide empty staff for multi-staff instrument (accordeon) doesnt work when chords are set between staves in grand staff.

That’s working as designed at the moment: you can’t show chord symbols between staves if one of the staves isn’t there…

Yes indeed…
It still is a serious shortcoming for accordeon parts (chords between staves always) that are playing chords symbol acompaniment without anything to play in the right hand (G clef) at the moment

Perhaps you could instead have two instruments assigned to the player, one with two staves, and one with one staff, show chord symbols on both of them, and then hide the two staff instrument when only one staff is required, and hide the one staff instrument when two staves are required.