Heart rate, ECG and activity are not working after updating to WatchOS 7

Tried to reset Apple watch from iphone, so iPhone removed watch from app. But watch didn't reset itself, tried manually from settings, nothing happens after tapping reset completely. Then I decided to restart my watch, and I saw setup screen, with prompting pin code, which is weird. Couldn't setup up watch because it says that this watch might be connected to some account. Found solution to factory reset apple watch by holding digital crown on setup screen. It is taking way too long. Once it will finish I will leave additional note

I’m having the exact same issue with my Series 4, and it’s entirely screwing up my sleep tracking (via SleepWatch) and my workouts, in that neither is being recorded properly, or in the case of my workout, at all.

No change after unpairing/re-pairing the watch. I’m about to ship this thing off for a replacement via my AppleCare+ coverage. Not a happy camper, at all.

I ended up also trying the steps of completely erasing/resetting the watch via settings to unpair it, then pairing it again as new (not restoring a backup). The issue seemed to go away for about 24-36 hours, where I was able to get a full workout and night of sleep recorded with no issues, but then low and behold this morning, I have the same issue of the heart rate sensor not working for large sections of my sleep, and during my 60 min run workout.

These are the two main things I use my watch for, and have consistently/daily for years. Fortunately I had a couple of months of AppleCare+ coverage left, and was able to arrange for a replacement to be sent to me ASAP, on the way now.

Same here, my Apple watch stopped recording heart rate and activity

Same here. Using the Series 5, bought just three weeks ago. Device working great until this update. Battery is also draining extremely quickly since the update: full charge at 1pm, 40% left at 4pm.

Unpaired watch and factory reset it, now heart rate and activity is tracked as before. Will check battery issue.

I did this and it worked! Problem solved. Cheers!

Maybe you should try complete factory reset, it worked for me. I agree this update is not the apple way with this amount of bugs, but anyway this helped me.