I have 27.2 developer beta running on my iPhone Air and Watch Ultra 4. My wife has an 18 Pro and also Ultra 4 but hers are both running the current public release versions of iOS 27 and watchOS 27. After 2 nights with the Ultra 4's, her sleep score is reporting accurate. Mine is way off. For example, last night we went to bed around 10 PM and woke up at 7 AM. Her scores were in the 90's with 7:36 hours of sleep. Mine is in the 40's with 4:20 hours of sleep. We both slept the same/great last night. Similar results for the night before - hers is accurate; mine are way off.
Health sleep score incorrect in 27.2
@EdMartin
Thanks for your first post. Its important to let you know that betas are to test your app for the new frameworks and functionality, betas should not be used on your primary device as some functionality may not work as intended.
When 27.2 is final and if you still having the same issue. I would suggest to better post at the Apple Support Communities:
https://discussions.apple.com/welcome
Hope this helps
Albert WWDR