AirPods connected but sound comes through IPhone

Hi, i've recently been having an issue with my Airpods. I think it started after i've installed the latest update.

when i put the airpods in my ears, i can hear the sound of connected, the headphone icon appears in the corner, but the sounds comes through the iphone. I need to go and manually select to play via airpods.

i've tried to re-connect the headphones, did not help.