Audio setup problems on LeEco X55 Android TV

I just bought a LeEco Super4 X55 smart TV that runs Android and installed Kodi via the Google play store. I have a custom built HTPC that has been running various versions of Kodi/Openelec/XBMC for years so I’m somewhat familiar with the setup. Anyway, the TV is connected to my Onkyo receiver via an optical cable. I’ve found that when I go into the Kodi settings and try to change the “Number of Channels” setting I get no audio output for anything except 2.0. Now if I switch over to my HTPC which is connected to the TV via HDMI (then to the receiver via the same optical cable) I can set the channel setting to 5.1 no problem and get surround sound. It seems to be only the TV app Kodi that has an issue outputting multiple channels. Not sure if this is even a Kodi problem or possibly a problem with the TV but any help is appreciated.