BLE. DataField. A device is visible for the simulator but not for a real device

Hello, 

I'm trying to connect a device using BLE. It works when I use the simulator. But when I run the DataField on a real device (Forerunner 945) it's impossible to even see it. (Checked with BleScan application. No luck. It doesn't see it)

The device developer said me: "The service UUID should be in the second part of the advertising package it sends", but I have not found any way to read (or get) this "second part of the package". The device is 100% visible for Android/Windows/iOS. 

Any ideas? 

Thanks.