Back flushing not happening

I have activated backflush in routing but when i am confirming the order goods movement screen is blank so i went to co02 and saw the BOM here backflush is not activted so i checked the backflush box and saved the order and again when i went to confirmation goods movement screen is availble with 261 movement.

here why the back flush is not happening even when i marked the backflush indicator in routing. it has happened for almost 20 production orders and it got stopped suddenly. But still the back flush is in active mode in routing.

so every time i am going to co02 and ticking the backflush in component overview.

I am using alternative BOM 2 is it effecting anywhere.

Thanks.