the setting "Prefer AC3 Passthrough" ie no 5.1 Surround Sound has just stopped working in the Apple TV App on Big Sur

I’m disabled with Quadriplegia Cerebral Palsy (basically that means I’m stiff and slow moving compared to everyone else) and wheelchair-bound. When it comes to using computers I can only use one finger with a Logitech Marble Mouse (Trackball) I've always used Mac Pros as they are the best aid for me.

A bit of back story first...

I've had a Mid 2010 Mac Pro for the past 15ish years (I had 2 of them, when one died I bought another - both Second Hand of course) To get Digital 5.1 Surround Sound with the Mid 2010 Mac Pro I used a Digital Audio Optical cable with this amp http://www.audioreview.com/product/amplification/a-v-receivers/panasonic/sa-he7-dolby-digital-receiver.html this is awesome with iTunes 5.1 Surround Sound movies with the "Prefer AC3 Passthrough" setting on.

At the start of 2020 my man sadly died she left me money for a brand new Mac so in May 2020 i got this...

2019 Mac Pro 3.2GHz 16‑core Intel Xeon W processor Turbo Boost up to 4.0GHz

48GB 2933 MHz DDR4 memory

AMD Radeon Pro Vega II with 32GB of HBM2 memory

8TB SSD storage

Stainless steel frame with feet

and to get around the annoying no input socket for the Digital Audio Optical I bought https://uk.creative.com/p/sound-blaster/sound-blaster-omni-surround-5-1 for the TOSLINK input only and still using this amp http://www.audioreview.com/product/amplification/a-v-receivers/panasonic/sa-he7-dolby-digital-receiver.html it actually worked right up to Big Sur.

Now with Big Sur movies never play in 5.1 Surround Sound "Prefer AC3 Passthrough"... At first I assumed I needed a new driver for my Sound Blaster Omni Surround 5.1 from Creative Labs Pte Ltd but I showed them this screenshot...

and they said this...

"Thank you for your reply.

By right, Decoding and passthrough are generally handled via the app itself, not the soundcard driver/software. So it has nothing to do with the driver. 

You are right on the set up similar to the previous one. However since Big Sur is just recently released update, we are not sure yet if there is any other configuration that you may need to do or confirm. 

Another thing you may check is the default playback device that your are using.

Ensure that you selected SPDIF out of the SB Omni Surround 5.1 as the default playback.

App configuration is important as well, as we do not have access to Apple TV app at this moment. We will take the standard VLC app for example. You can try VLC to double check if this is an app related issue with Apple TV in this case.

After checking and confirmed the setting, playback a file that is originally Dolby encoded

If you do not have any locally stored Dolby File, you can download samples from here, https://thedigitaltheater.com/dolby-trailers/

From the menu, select Audio > Audio Device, then select the device that you would like to play the audio from.

For the Omni, under Audio devices, you should see something like Sound Blaster Omni Surround 5.1 SPDIF out (Encoded audio) option. You can select that and check if the passthrough feature works on this app."

Basically Creative Labs Pte Ltd said its up to Apple to fix the Digital Surround 5.1 Sound.

HELP :) I really want "Prefer AC3 Passthrough" ie 5.1 Surround Sound working again in the Apple TV App on Big Sur with my set up.