Ps4 connected to receiver w hdmi. Audio settings on ps4 primary output port= hdmi. Audio format priority= linear pcm. My receiver tells me what format is currently being sent. If it's pcm the speaker icons are lit up for the corresponding channels.Need more info,
How is your PS4 connected to the receiver? How do you know that you aren't getting 7.1? Do you have the PS4 audio configured for PCM via HDMI?