I am having the same problems. I have checked all Audio settings, including Composition (Preview), but in CC2018 Ae, it only then offers options “Play Current Audio” or “Audio”. I clicked both, still no sound. There is also no “sound” icon to the left of the mp3 file. I’ve clicked the audio icon in the right panel by preview, still no sound. But, I am getting sound on Google and with all my other files.