I got a similiar problem like yours, I don't know if it's the same but you do have throwables in your gear right? And they don't appear next to your ammo hud like the "x2 Smoke Grenade" right?
And you can't throw them right? xD

Well just drop those throwables and put them back in your inventory. They should appear in your hud then.

Yeah it*s a bit buggy. Throw them all away and pick them up helps.

I will try this work around. thaks for the replies

Or just only drop one nade and take it back.