>>337384459
This is a common issue with the valve index.
If someone is telling you "works on my system eksdee" they are one of the single digit percentage of people who are able to use the passthrough cameras.
I sometimes can enable it without having made a single change in my settings. But that is only good for 5 minutes and then it won't work again.
Why? Beats me. I have tried what I have found on the internet, including >>337384854
but nothing seem to work.

It is just how it is.
Just use the old analog passthrough
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