Won't print in black and white

[Android Central Question]

I print wirelessly from my tablet, but if I want to switch from the colour original to black and white, I toggle the option, it stays put, but doesn't change the screen image to b&w (which it should) and prints in full colour
I know it should work, because it used to. What has happened?

 

[Rukbat]

Communication between the printing app and the printer? Have you updated the printing app recently?