You seems to have gone through most of the steps that i would have thought of.
Appears your output is set right. I would try maybe disabling and re enabling it.
That you had it working on the receiver before.. it should need to be on that same input. Usually you have to define on that input, that it is is to use that as its input.
But if it was working before, that should be set alright.
Re-seat the cable? make sure its making a proper connection.
My only question.. you say the regular TV/PS4 works.. they are going into the TV and then out to the receiver? And they work?
Sounds like it should be then a setting, specifically for any 'apps' on the tv itself?
I have a 2+ ish old samsung TV (Forget the model). And i use the optical out on it to my AVR.. specifically for the smart TV features. And works just fine.
Rogers 9865, LG 47LV5400 LED TV, Onkyo HT-R690.