"Export Parts" Results in 63 Bars of Rest

Hello,

I am trying to export my score and individual parts to PDF. My full score is exporting as it should, but the parts are not. When I export parts, they show up as just 63 bars of rest and no notation. It does the same thing when I open the parts separately in MuseScore.

Attached are two files- test.pdf is how the parts are exporting, and Brass Bonanza fr.mscz is my full file.

I am using MuseScore 4.