Why is the audio not playing on iMovie?

No audio appears to be playing on iMovie. I am unable to hear any sound from video clips that I've added, any music tracks I've added to clips, or even the sounds/music itself in the music/sound effect section. Strangely enough, when I roll over those clips that are supposed to have audio, I can see the volume levels changing, yet I still hear nothing.

When I export the project, the audio plays fine on Quickplayer, but I just can't hear it on iMovie. This is incredibly frustrating as I cannot even hear what I am adding to my project. I have never had this happen before. The volume on my computer works fine so that's not the issue. Does anyone know how to fix this problem?