SL8YG LG soundbar - "NO REAR" Error. Please help.

I have a SL8YG LG soundbar, the sound works when I'm gaming on XBOX or ps4, but not so much when I'm watching movies on my XBOX. I keep getting an error on my sound bar that says "NO REAR" and the sound cuts off for a second. The sound eventually comes back. Any ideas on a solution?