Something in the new relationship editor, when editing a band that has several members.
I cannot say if I like it or not, feature or bug.
In Members or in Original members, when you click Add another artist 
button, all instruments and vocals contained in the pre-existing members will be copied over
When I recently added a new band, all members played different instruments, so it was a little bogus, as I had to delete growing list of pre-filled instruments for each member.
But when you edit existing band, maybe it can help… 
