To answer your question, I'm not sure what would be happening on the software end. I played a variety of file formats (mp3, flac, wav) all with the same issue. Although my solution was just pushing the jack further into the device...
I'm having the same issue- no audio comes out of the right channel no matter what wired headphones I'm using :-( Although when I use Bluetooth (airpods), the audio is normal, in both channels.