@stephenrobles Made an unfortunate discovery about rocking an older Apple Watch with an Ultra 4.
So … I can confirm once you have slept a single night with a newer watch from that moment on no health data is synced back to your iPhone from an older health sensor watch.
You can look at it your sleep data on the watch itself, but very odd and frustrating because the type of sleep you are in should not be locked to the new watches; it won’t even send over basic heart rate data.
@stephenrobles Prior to me doing a sleep with the ultra 4 capture continued on series 9 for all data. I would wear the 9 at in evening after work and ultra 4 during daytime. Both would capture and send data until I did a sleep session on the Ultra 4.