Xiaomi Mi Band Timer Problem

 All Xiaomi Mi Band smart bracelets seem to have a problem with countdown timer: sometimes it doesn't alarm is proper time. But alarms only when you are activating screen for some reason.

At least it is so on Mi Band 3, Mi Band4 and also on Mi Band6 which I have just boughtand about to return.

So sorry because these bracelets are just perfect for me in all other ways