Mi band 2 no longer measures heart rate when tracking sleep in sleep as android

Detailed description of the problem:
I have enabled heart rate monitoring in sleep as android as well as heart rate monitoring and sleep as android in notify & fitness, but when I start sleep tracking, it only tracks sleep with the mi band 2 without heart rate monitoring, it used to work before, but not anymore.

Steps to reproduce:
Go to sleep tracking in settings then select accelerometer in senor section, next go to wearables section and select use xiaomi mi band with notify & fitness and enable heart rate monitoring, next enable sleep as android in notify & fitness and click settings in the sleep as android section in notify & fitness and enable heart rate monitor and when you start sleep tracking with sleep as android, you will see that the heart rate senor is not lighting up on the band.

Version of Sleep as Android:
Version of Notify & Fitness