Apple Watch 8 not Tracking Sleep & Sleep Stages

Hello all,

I have an Apple Watch 8, running 9.5 (at the time of writing). This is paired with an iPhone 14 Pro running 16.5

When I first got the watch, an upgrade from Series 5, the sleep data appeared perfectly, showing stages and tracking correctly. This was working in tandem with AutoSleep which I was previously using. No issues for the first couple of weeks, then suddenly, the Apple Sleep was just showing the block of time my phone & watch were in 'Sleep' Focus, with no information on the stages. Some nights NO DATA is recorded at all. The sleep graph in Health.app is absolutely empty. Other nights I see only the green bar showing time asleep and time awake, but no stages. And that data is absolutely wrong. For example, tracking starts 3h after I have gone to bed. I regurarly sleep 7-8h and the Sleep in Health reports 1-2h of sleep.

Every once in a while everything is tracked perfectly....like every 9-10 days. Last night's sleep was tracked correctly. The night before the graph was absolutely empty. Today the graph is a mess with wrong data, a green bar only, and no stages.

I have tried:

• Verified all tracking metrics are on and allowed under privacy;
• Ensured wrist detection is turned on;
• Kept watch charged (always 100% at bedtime);
• Made sure Sleep Monitoring is turned on on Apple Watch;
• Deleted current sleep schedule, turned phone & watch off and on again, then set up a new schedule;
• Deleting Autosleep from both phone & watch;
• Turned off 'Track time in bed' on iPhone;
• Made sure Apple Watch 8 is first in the 'Data Sources' for sleep;
• Reset the watch entirely to factory defaults, then paired it up again;
• Turned OFF "Share Across Devices" in Focus (off on ALL devices).

Sometimes it will randomly track again for a couple of nights & then go back to tracking nothing or tracking wrongly.

This is super frustrating as it links into my fitness apps, which all think I am now not getting enough sleep so they adjust metrics accordingly (wrongly).

Any other solutions people have found other than those already tried above?

I'm in touch with Apple Support over the phone for 2 weeks now. Support is super kind and helpful, but they also can't figure it out. The issue has been escalated. Support has done Screen Sharing, checking settings, and adjusting things. I test Sleep for a few nights and then I call back (the same person via a special link) for further troubleshooting. So far, no good.

Any feedback and suggestions are very welcome.

Thank you!