bluetooth connection

Devices:

iPhone 6 64GB, iPhone 6 16GB, iPad Air 2 128GB, iPad mini 16GB, iPad 2 32GB

OS:

iOS 8.2

Problem:

Non of the above iOS devices would connect to the iGrill mini / Kitchen Thermometer mini from iDevices - bought via Apple Store (online) - via bluetooth.

Already tried:

The devices (iGrill mini / Kitchen Thermometer mini) are switched on, blue light is flashing. Both can be found via Bluetooth from my Lenovo X1 Carbon.

Toggle Bluetooth on to off to on does not help with the problem, nor does a restart of iOS Devices help.