Did you Disable HDCP, maybe that's the problem. Turn it back on to see if it makes a difference too...
my HDCP was never disabled, and disabling it actually makes the problem worse.
I am on an HDMI switcher that also outputs to TOSlink, so I've been sending audio through HDMI to it, then the switcher sends the audio to my reciever via TOSlink.
It worked just fine before 1.70. Toggling the "output 5,1" checkbox doesnt help either. I forced my switcher to 2.1 mode and it plays the audio just fine.
Something changed in the PS4's audio output that is fucking up the switcher/reciever.
When I get home I am going to see if my TV is a decent passthrough, and bypass the toslink audio out from the switcher to the TV and see if that works out better.