Device settings in Connect Mobile?

Just received a Vivosport, a replacement for the faulty first unit.
The first one appeared to not work properly from the start, so I am pleased to note that this one works very nicely out of the box with all notifications and alerts being passed to the watch (watch sw version .2.7)
My question is, under the device settings in the Connect mobile app 'Bluetooth Connection' in the Notification and Alerts section is turned off.
I am confused by this setting especially as it is all working very well.
Can any one explain the logic here please.