Ah shucks,
I recall an issue like this by means of a audio setting on the receiver with a Onkyo. It did not make the Center Speaker work (but 4.1 worked) with a setting called Center Wide. Once he turned off Center Wide, 5.1 worked perfectly. I dunno the setting on a Yamaha AV, but worth a check mark point.
Also
I have my sound card setting as follows (both SBz show activity but look at the default)
Corsair 500R Case, H110 Hydro, 1200AX PSU, Asus Maximus Hero VI MB, Intel 4770K CPU, Gigabyte GPU GV-N98TWF3OC-6GD, G-Skill Trident 2400MHz 32GB, Crucial M500 960GB SSD, Seagate 6TB HDD x2, Creative SBZ to Denon AVR-4311ci - Infinity Primus 5.1 w/Klipsch Sub XW-300d, HP ZR30w 30" S-IPS LCD, W10 64bit