Same issue here. I've seen last HR was 1hr ago twice... most I ever saw previously was in the 20 minute range.
What I don't understand is that the glance can pick up my HR within 20 seconds no problem. If the IR sensor doesn't capture HR after 10 minutes, why isn't the green LED coming on like Apple says it does?
I did a 30 min indoor cycle, ended the workout on the watch, then took the watch off to take a shower. Noticed that the green heart rate monitor lights were still on a good 5 minutes after I took the watch off. Never noticed this happening before the update.
I had to restart the watch to shut the lights off. I don't know if I would have noticed this had I not taken the watch off, which is concerning as it would have burned through battery life.
Yep, same problem with me... I noticed my exercise ring is unusually empty today despite having been on a Physical Education course all day.. checked data in Health and HR data looks accurate but very sporadic.
Clearly a problem created by the new update which is really annoying.
I also noticed that my heart rate data in the health app for about a week period is gone and my heart rate data is now updating into the app intermittently. I spoke with Apple customer service this morning, but data could not be restored and their advice was to restart both the iPhone and the Watch, clean the sensor back, and keep an eye on it. That, unfortunately, has not fixed anything and I think there might be a bigger problem on our, er, hands (or wrists).
I just got mine yesterday so I can't do a before/after comparison, but I can tell you that the only logs I have are the ones where I have manually measured my heart beat. Seems to not do it in the background at all for me.
So having restarted both my iPhone and Apple Watch my heart rate detection seems to be back in a regular rhythm... Will continue to monitor but the last four measurements have been taken every 10 mins.
EDIT: Spoke to soon... its all gone erratic again!