Apple Watch Ultra heart rate not updating on watch face after watchOS 27 update

Hi there please try this

Toggle Heart Rate Settings on Watch: Open the settings  app directly on your Apple Watch. Go to Privacy & Security (or Privacy) > Health > Heart Rate. Turn the switch off, wait a few seconds, and turn it back on.

Check Background App Refresh: Open the Watch app on your iPhone. Tap General > Background App Refresh. Make sure the main toggle is on, then scroll down and verify that Heart Rate is enabled.

Restart Both Devices: Turn your Apple Watch and iPhone off and back on again. This clears stuck cache loops that prevent complications from polling data in the background.

Re-add the Complication: Long-press your watch face, tap Edit, and remove the heart rate complication. Save the face, then go back into edit mode and add it again.

Unpair and Re-pair: If the complication still fails to refresh on lift, open the Watch app on your phone, go to All Watches, tap the "i" icon next to your device, and select Unpair Apple Watch. Set it up as a new watch to clear corrupted system files from the upgrade.

Ok problem solved, although not sure why. Worked my way through the suggestions and none worked until I reached the unpairing option. At that point noticed watch was low on charge so put it on charge for a couple of hours …. And afterwards the heart option started working… and still is , so happy bunny

So hold on. Your watch ultra 4 shows heart rate on wrist down when in always on display mode ??? I’m on 27.2 and since day 1 is doesn’t show it. Just says heart rate and it’s a blank graph.