Beta 18.20 Low heart rate

50bpm for resting HR is possible, not weird. But it depends on the person. But if it is half of what it should be, you say your resting HR is 100 under normal circumstances? Well, I can tell you, that is not normal, but fairly high. So check which HR you are comparing. High, Low (resting) or average.

Resting heart rate is normally 60 bpm as you can see from the image.  It appears to be measuring half the actual value, going down as low as 50 or lower bpm, which the device logs as a resting heart rate if it stays at that rate for 5 mins.  You can see the average is 62 for the week.  Dropping 12 bpm in a day is not normal under any circumstances. 

My resting HR is usually between 48 and 55. That mostly occurs during the final hour of sleep.

My daytime HR is usually in the low 60s when I'm not doing anything, rising into the 70s when I've recently eaten. During a hard run my HR might go as high as 180bpm.

What's normal for you?

Yes,  I am awake and having a value lower than that is typical for me overnight. Overnight usually 60 to 65 and now during the day showing 45 to 46.  I checked separately with chest band and it is off. 

Chest band with my edge 830, not my forerunner. 

Well, there is no scale or values on the axis, so I only can tell by the numbers you present. I did not know the 62 was/is your weekly average. I looked into my COnnect page and have the following overview:

So now I understand your issue is about the relatively big gap between weekly average and the daily rest HR. In my case those are closer together, which makes more sense, I agree with you.

My overnight HR can drop to 46, but average is also around 52/53