Adding a track disables the "play" functionality

Hi there. I’ve been using Audacity 3.5.1 on my Mac (OS Sonoma 14.5) for as long as this version of Audacity has been available. I’m encountering a new issue where adding a track to a project disables the “play” functionality. For example, if I add background music to my voice track, the play button no longer works. Has anyone encountered this? Thanks, Kristen