I'm assuming Crytek has no answer for the problem of being unable to pick up and use C4 and the JAW. I've run through the game a few times and if one can't use the weapon, it makes for a tiring and boring experience.

If there is a bug and Crytek has a fix, where is it???

You need to have grenades out to pick them up. They are both classed as an explosive, so you have to choose between grenades, C4 and the JAW.

I think he's talking about single player, where you can have all 3. Picking up weapons in general is a bit annoying, cause you have to be looking exactly where the game wants you to ffs. When picking up C4 I usually just mash the F key while moving the camera, hoping the game is nice enough to let me pick it up.