5.1 Surround Sound Not Working

I’m new to Kodi and not an engineer so please keep this in mind.

I use my W8.1 PC to play latest version of Krypton 17 through a Sony STR DH550 (DTS/Dolby True HD) to the TV via HDMI from the onboard MOBO. The system has played perfectly without Kodi via an Xbox, but since using Kodi, only the front/center speakers work and at a rather low volume. All the speakers work fine in DH550 speaker test. I have tried numerous movies like Jason Bourne, etc. that don’t have fake sound.

Kodi audio settings in Expert:
Number of channels – 5.1
Output configuration – selected
Stereo Upmix – selected
Passthrough – selected
Dolby Digital capable receiver – selected
Enable audio DSP processing – selected

What am I missing here?

Thanks!!