Grenade key threw grenades before but doesn't now

[Schnippshly]

In the beginning of the game, I was able to throw grenades by pressing the grenade key. After quitting the game and turning it back on, grenades no longer get thrown by throwing the grenade key. It's really inconvenient to have to pull grenades out in the middle of a fight when there's supposed to be a key that instantly throws them. Why can't I throw them with the grenade key anymore?