Musescore 4 only playing one staff

I have been using Musescore 3 up until yesterday. Today I opened a project from Musescore 3 in Musescore 4 for the first time. When I playback the score, only the drums play. I attached a picture of the mixer panel. You'll notice that the Mute buttons are blue on all the instruments except the drums. I cannot press the buttons. If I press M twice when in mixer, the score plays all instruments, even exiting out of the mixer. However, if I make any changes (move a note, copy and paste something) it suddenly only does the playback of the drums again. I'm wondering if this is a score problem or a Musescore problem.

Ok I just opened another score to test. Same issue. It is only playing the top staff, which in this score is trumpets. In the previous score, the drums were the the top staff. Not sure what this means.

Unrelated, possibly, but I'm getting an error message when saving the second score: "Your score could not be saved to the cloud. Please try again later..."