No surround sound in a PS5, LG OLED CX and Anthem MRX 720 setup

Firstly, you will have to excuse my English – but here goes! J

I have a PS5, an LG OLED 65CX TV and an Anthem MRX 720 receiver where the latter – as you probably know – does not support HDMI 2.1. I have connected my PS5 directly to the TV and I am able to play games in 120fps but I have trouble with the sound as the Anthem now shows PCM 2.0. Shouldn’t I be able to get some kind of surround sound in this setup?

On the PS5 – in the audio settings – I have chosen "AV amplifier" under "HDMI device type" and in the "Number of channels" section I have chosen "5.1", as this is my setup. I have also tried various settings on the LG TV in the “Sound” section but as stated earlier, the display on the Anthem shows “PCM 2.0” no matter what I do. I have naturally also experimented with settings on the receiver.

So, do you have any recommendations to the sound settings on the PS5 and the LG TV (“PCM”, “Bitstream” etc.)?

I have read of different solutions from HDFury (“Hdfury Arcana”) and Thenaudio (“SHARC EARC HDMI”) and could this be the solution?

Thank you very much in advance and best regards

Just out of curiosity, did you try “number of channels” as 7.1?  I’m wondering if the Anthem is defaulting to stereo because it’s trying to find a sixth and seventh channel.  Have you tried asking Anthem?
Another thought: have you tried another source besides the PS?Maybe you can borrow a cheap Sony Blu Ray or DVD from some friend, or pick one up from a charity shop, and see if you can get MC.  And has the PS played in MC with other equipment?
How are you getting the sound to the Anthem?  If you are using the toslink output on the TV, it is likely that the TV is down-converting the sound data to 2 channel PCM.