Musescore website not letting me isolate parts

So we use Musescore for our acapella group. I recently edited a score and then uploaded it online, so the rest of our members can easily access it. It's really helpful when everyone is able to isolate their specific voice part while learning the music, but for some reason, my most recent score isn't letting you do that. When you click the instruments tab online, you'll find that it thinks the entire score is the "solo" line and nothing happens when you try to mute the soprano, alto, tenor, or bass line. This does not happen with the score I've created directly on my computer, only when I try to isolate the parts online. Please help! https://musescore.com/user/29563521/scores/5373529