I decided to try removing the magazine from the gun to put more bullets into it. Once I finally got it out of the gun which was troublesome in itself. It fell to the ground and was no able to be picked up. I tried using vicinity menu and holding the gun out and pressing R2 on the magazine while it was on the ground. nothing worked. Lost my bullets and the magazine :/

I left the game and came back immediately to find that neither my bullets nor the magazine was where I left them on the ground minutes ago
This happened inside a small apartment building

The prompt to pick up the magazine flash quickly when the button was pressed but nothing happened.
This happened to me on only one occasion so far. Will try again whenever I get the chance.