This is a confusing conversation, because as far as I can tell the definition of "a flashbang" is changing between:
1) The projectile
2) The flash/blinding effect
As far as I interpret it, Grapen wants to block both the projectile and the flash effect, but I think one or more people are only considering one definition, which is the source of the confusion over whether the game is bugged or not.
I think.
Maybe.