I know you have said the cable is fine but does it connect the phone etc. to a computer as a data device and allow you to, in principal, transfer data to or from the phone from the computer?
A cable may charge the phone from a PC or the controller but that does not means it is capable of transfering data, which is what the App needs.
This cost me hours as I swore the cable I was using was good. That said could the socket in the phone be going? The one in my Note 4 has, possibly because of the 'hammering' it got during my attempts to connect it to the controller with a charge only cable.