Note Stems Not Scaling with Hidden Note Heads
When setting (non-middle) notes of a chord to 'Not Visible' the stems of that chord do not also scale their visibility. The result is a stem that extends beyond the note-heads.
One use-case where this is a hindrance: Using a single staff to create two parts - one chord-melody part and one that is the simple, single-note, melody line only. Rather than manage two separate staves for this it would be easier to be able to manage (compose, edit, etc) on the one staff and be able to simply hide the chord's harmony notes in the simple melody line part.
The work-around is to create a 2nd staff and delete the notes on that staff that you'd otherwise set to Not Visible on the 1st staff.