Thank you for replying. With the help of some experienced riders, the problem had been resolved.
The App does not allow the Bluetooth to be connected to other smart devices (smart watches, health bands etc) while scanning for the DYU.
Temporary solution is to switch off or unpair the smart devices, but a more permanent solution is definitely required.
Please do look into it.
PS: Problem occurred on Samsung S8+ with Garmin Fenix 3 and Samsung S7 Edge with Miband 2. Hope this help with your technical team.