How can I resolve audio problems in iMovie projects?

i’ve been working on a youtube video for a couple weeks and there are a few sections of it that use background music, taken directly from imovie’s library. i haven’t had any issues with it playing until today. after i waited for everything to download, i started editing but the imovie music won’t play. it shows up in the project exactly how i put it and the audio for everything else is working just fine, but for some reason just the music from imovie won’t play. i double-checked to make sure it’s downloaded and it looks like it is. it’s not muted either. what should i do?

[Re-Titled by Moderator]