Recently picked up a receiver + external audio system and I'm having trouble getting my android TV connected to the system. The TV I have supports ARC but my receiver does not, so I purchased an optical cable for the sound output.

I've connected the optical cable from the TV to the receiver but cannot get the sound to come out of the speakers. I have ensured the receiver is set to the correct channel (TV Audio in the case of my denon), have selected "external audio system" in speaker settings on my android TV and have selected "PCM" digital output audio settings to no avail. I have also tried checking for updates to the android TV, doing a hard reset of the system, and unplugging and replugging the optical cables but none of these worked.

I've done some googling and at this point I've more or less exhausted all the troubleshooting options I've come across on other help sites or online forums. Anyone have an idea of where I can go from here?