5.1 audio not working over optical cable, with proper codecs in place

Hello! Just wanted to submit a bug I have run into relating to the audio on my PC. I am trying to get Final Fantasy XIV to work in a 5.1 DTS setting, running through optical (SPDIF) cable, but can only get it to output stereo in this manner. I am looking to make this happen through the onboard audio on my Asus Z87 Pro motherboard, which uses an ALC1150 RealTek HD audio system. This setup includes a DTS Connect audio codec, which should encode the signal and allow for surround sound to work no problem. What's odd is that my receiver switches over to DTS mode when receiving audio input from the game, suggesting that everything is coming through fine, but sound only comes through the front speakers. I am able to make all other games that offer 5.1 support run using this set-up (eg Borderlands 2, Skyrim, Dishonored, and others all work fine), but of course, the only one I really care about - FFXIV - is being stubborn. Please, let me know if you would like more information related to this issue in order to solve this bug. Otherwise, I hope to enjoy the world of Eorzea in 5.1 sometime in the future, thanks no doubt to the hard work of the many talented individuals who work on the FFXIV team. Cheers!