Why sleep data is not showing the details? (Sleep track is enabled on watch)

As we can see, the Apple Watch can give details about sleep in each stage of sleep here

Track your sleep on Apple Watch and use Sleep on iPhone - Apple Support

See the section "View your sleep history"

I have everything turned on as per this support article.

Many other answers in apple discussions say that its third-party data. I am not sure if anyway paid attention to apple's support article.

Plus, being an iOS developer, I know that they have everything that is needed to record the data, a gyroscope, heart rate monitor, and Oximeter, you name it. So Apple dont need to depend on third-party data or devices, IMHO.

But then why do I dont see the sleep data?

And here is the kicker, I have had Oura's ring past 2 years. It was a third-party thing it would still have data.

So that claims rest in peace.

Can it be possible that apple has a bug and no one paid attention to it, as how many of us pay attention to our sleep?

If anyone knows the answer/hack/workaround. Please reply. I would love to have detailed data on my sleep.

Best,

AC