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.