To reply to
@Dadam and
@HobbesOnTour
Yes, the problem is completely with the phone. As previously stated I never had an issue with my older Motorola. Have successfully paired the cycle computer to my wife's mobile and no problem.
Motorola (Lenovo) help desk have been sent lots of files from the phone but "can see nothing wrong" but they would say that!
Reading the Lenovo message board I am not the only owner to have experienced a similar problem with this model of phone.
As time has elapsed and newer models have been released any urgency in finding a fix for this model are well and truly down the priority list.
I think my state of "not really trusting the Bluetooth functionality of my phone is what is steering me towards a watch with WiFi capability.