I wrap the 2 wires (blue and white) together, in the same way in the case of white ferrite and blue ferrite.
I connected the white wire of one side to the blue wire from the other side - this is the common end. Then I used the remaining wires to connect to the circuit as in the schematics.
I unwrapped and wrapped again starting opposite direction. I used grey ferrite core. I switched the ends. No way. Silent LED.
One moment I thought there is very low inductance in blue ferrite (for unknown reasons), so perhaps more winding would help.
The method is here (but it is detailed in many other web-sites)
and a more kids friendly desccription here: