Heart Rate monitoring unexpecdly drops to low values during workout

I have the fenix 5x plus and it is not the sweat. Today i did 2 spinning rides.  Before to start I cleaned up my watch to be sure the sensor was clean then i did a soft-reset (as garmin support asked), then i shaved my wrist (as garmin support asked).The first ride (50 minutes) everything was fine and my app (the one i m developing) worked fine. When i started the second i cleaned up the sensor but i didnt execute the soft-reset. After 30/35 minutes the sensor start dropping HR and wasnt possible to let the samples goes over 140 bpm. I m sure i was more than 160 beacuse i start to sample the HR manually with my finger on neck and i was almost over 160. Then i tried to move the watch up and down on the wrist, change the wrist, dry up my wrist and the sensor but nothing! One of the most important thing is that when i took off the watch HR doesnt fall to zero for more than 5 minutes!!! BPM remain around 130/140 bpm. Then I close the app and open it again and everything start to works normally. ini the following picture you can see the entire activity and then when it start dropping. 

So 1st if all you're in the wrong forum if you don't have these problems on fenix6.

Can you see what the hr is in the built-in heart rate widget when you think it drops in your app? Does it agree with what you see in your app or with the higher value you think is right?

Do you have any other device that can measure hr?

I did this too! When i close the app and the HR rate is wrong, the built-in heart rate widget starts from the last value retrieved by my app and then seems to work fine and correctly follow the  heart-rate. So if HR is around 130bpm for example and i switch on the build-in widget it starts from 130 and rise up (if still under activity) reaching the correct bpm.

My second device is my finger on the neck... not very confortable but it works fine when u need to check the bpm

My friend has the fenix 6x plus and have the same issue. 

Had this issue today. 6XPro, 24.78 alpha. Garmin HRM strap. Never had it before.

well I don't know, but if the built-in HR widget gets the correct value... I know it sounds not very logical but maybe there's some strange bug in the app?

Hi Gavriel, I think that's exactly the point everyone here is making. If the HR works well in some apps (like Bike) and fails in others (like Backcountry Ski) it's got to be a software bug introduced in a recent update

no, I'm trying to tell that the bug might be in the CIQ app

thinking about your words i had an idea: in my application i add the chance to collect the HR sensor data every seconds (how it is supposed to be) or every 1 to 5 seconds. In my mind (i'm an hardware engineer... i'm sorry nobody is perfect) it is growing the idea that the fw driving the sensor, sampling each second, could crash somehow. So i'm trying to slow down the HR sampling. This could explain why some apps are working and other not (data sampling algorithm change from different sports). Anyway sampling HR each second could be useless too...  

I'm not sure I understand. That 5sec sampling sounds strange, you should instead use what other ICQ apps do, but from how it sounds (without seeing the code) this shouldn't give you too low HR values anyway (unless you have a bug in the code :) IMHO reporting every second is OK but there's a "better" way though: only report the values to fit when they changed, but this adds some code, memory overhead.

You can have the instant HR but what kind of information is giving to you? well, i use to average the HR in a period such as 15/30 seconds because during the activity your HR does not follow your strain, there is always a delay. So, sampling hr each seconds or every 5/10 seconds doesnt makes the difference in terms of "HR information". I tested my app with a chest band and my fenix 5x plus and it works fine (actually it works for me) so we can say the code is correct. I'm going to check the fenix 6x plus with a chest band because the wrist sensor is really a mess!! Next week i will have some more data to discuss with you all!! Enjoy this 2023!!