How do I pair external bluetooth keyboard to ubuntu touch phone (Aquaris by BQ) build r22?

Behaviour:
Keyboard is recognised by bluetooth manager, but button is & stays grey unable to pair.
To pair it on other OS (Android,iOS,Windows)it always first displays a dialogue with pairing request such this similar example on android:

Such pairing request window never displays on Ubuntu Touch :-( Keyboard is model Flyshark by iLepo.
There is untested solutions using which involves developer mode using apt-get to install bluez-compat package https://www.wayneandlayne.com/blog/2010/06/14/bluetooth-keyboard-pairing-without-code-entry/
Update: (r24) the problem remains, dialogue asking for pin shows (picture bellow). I'm able to type the number, but not find out what the numbers are :-(

