pooh eating persists?!?

good evening everyone.

 a few weeks ago i asked about my one chicken eating its own pooh  well its still happening and i dont know why? they have now been properly wormed with flubervet and im still using verm-x on them evry month.

any ideas as to why she is still doing this? and any advice to stop it from happening would be greatly welcome.

thanks kellym

have inspected thier poop this morning and no signs of anything strange, just normal unappetizing looking pooh so i still have no clue as to why she seems to like it so much