"Phantom" instruments in part scores

I'm working on a piece, and I decided that I wanted to have separate scores for the different instrument families in addition to the main score. So, I opened the parts dialog and created woodwind, brass, and percussion part scores, however, when creating the brass section score, I accidentally added the marimba to it. I quickly removed it and finished up with the process, but when I went to the Brass tab, the marimba was there anyway, just without a key signature, time signature, or any visible notes or rests aside from the multi-measure rests that the other parts share. I say "visible" because it can still be heard during playback. Any idea what's causing this or how to fix it? I've attached a screenshot showing what it looks like.