I've searched everywhere for solutions and I've made sure all of my render settings are correct. I've tried everything. I've tried rendering different file types and still no audio but for some strange reason it only renders audio when I select Windows Media Video (.wmv) file. It renders fine and with audio. But I would like to use .mp4 because I'm in a film class that uses macs and when I'm in film class the macs can't view .wmv for some reason and I use my own windows PC to edit. I'd like .mp4 because it is simple and view able on all formats. I even tried using handbrake to convert the .wmv to .mp4 but there were encoding and sync issues which I also tried fixing but when it did convert I suffered quality loss. Please I would appreciate some well needed help. Thank you.

UPDATE: After playing around I found that if you select the whole video under loop region and use that as a render region while rendering it grabs the audio. But I'd still appreciate an explanation to why it would not render audio before this.