Mono Voice Over (recorded on Multitrack) Only Plays out of one channel once exported

I have the latest version of Audition, and out of nowhere this issue started happening. I didn't change anything, it just started out of nowhere.

I use Audition specifically for voice overs, so I record in mono. While I am editing (both in waveform and multitrack) I can hear the audio perfectly from both channels. But now for some reason once I export it, there is an electrical buzz and it only plays out of one channel (using either headphones or speakers). 

I tried the very same exported audio file on a different computer with different speakers & headphones, and it is totally fine. 

So I'm at a loss. Any advice would be appreciated. Thank you.