4K capture does not work for two months

I have the same problem, everything worked before, it was months ago that I capture in 4K and since yesterday impossible to make a capture that works beyond 1080P

And even after two months we have no fix for 4K capture issue.

I'm sure people are losing trust in Microsoft
because this is too much
to be ignored

Same problem here.

Two different Xbox, different USB 3.1 sticks and same result.

4k capture are corrupted after 2 sec.

The funny part is this was working really well before they updated the way we capture gameplay.

Why are you wanting to capture at 4K? the Xbox One S doesnt render any game at 4k, so all you will be doing is capturing an upscaled image.

IGN does have a really good walk through on how to make sure your 4k capture is set up, but perhaps have a look at the different saving locations? it could possibly be saving to another destination that you're unaware of. But also, be aware, that 4k videos,
even SDR and 30 seconds long, can be larger than you'd expect.

capture 4k on xbox one x

The capturing was a problem for a while on the one dashboard, so hopefully its fixed for you now.