fenix 5 huge battery life drain when HR in "---" or "Measuring" mode

Battery life is fine until my fenix 5 can't measure my heart rate. Then the drain is huge. For example: I check my HR, everything is fine. After an hour or two i check it again. This time it's in the measuring mode and my battery is 30% down from the last check. If i don't check it will drain the whole battery. That happens sometimes when I go to sleep and when i wake up my fenix 5 is dead. This is a massive problem. I cannot rely on it.

When i see it in measuring mode i restart it and then HR starts working again and measured successfully.

As you can see that one hour(even less), when my fenix couldn't measure the HR, corresponds to the steep decline in battery life(Around 30% !!!)

What's going on Garmin? I don't plan to check my HR every half an hour to see if it's measuring and draining my battery!

Here is another photo of "oh i just can't measure you heart rate...sorry...just gonna drain your battery"

-------------------------------EDIT------------------------------- 

It's not directly connected to the Heart Rate feature. I tried turning the heart rate feature off and the same thing happens, but this time I have no way knowing that the watch bugged up(I used to just check the Heart rate and if its in the "---" mode I restart it), so it just dies on me.

Again the problem disappears when I soft restart the watch.