There is a bug with the Roku Ultra 2022 - no combination audio configuration remedies that Roku is only outputting stereo audio in Channels 1/2 even though the content YouTube TV references AC-3 5.1 audio (Youtube TV - > Stats for Nerds).
I've verified with an Atomos Ninja V+ that Roku is only outputting stereo audio in Channels 1/2. I've tried every audio setting that Roku makes available.
It would be great if Roku and YouTube Engineers tracked this down...you can reproduce/validate this with an Atomos Ninja V+ and an HDMI 2.1 splitter (https://www.amazon.com/dp/B0CXXN58DJ?psc=1&ref=ppx_yo2ov_dt_b_product_details)
An Apple TV 4K (2022) does not have problem - I see 5.1 audio in the leveling mixer, with the announcers in Channel 3/4 for a sporting event. I'm using the Michigan vs. Ohio State 4K game + Wimbledon tennis to validate the 5.1 audio being present (again, should show AC-3 if 5.1 is available, otherwise it will show m4a, which is stereo).
Feel free to email me, I can reproduce and validate this bug all day - *******@gmail.com