Infinite Ammo breaks when reloading save (all episodes)

[ProbablyWorth]

I finally managed to 100% IV and ran into a bug where the ammo I got over the regular limit was gone after reloading the save.

The reward for 100% completion in GTA IV is a "100% Game Completion." message in the top left corner and gives players the ability to buy an unlimited amount of ammunition for all weapons, although it still costs the same as before,... This reward has a bug that is present when the player loads a 100% saved game, which causes all the ammo that was over the original limit to be lost.
-GTA Fandom Wiki

Apparently TLaD and TBoGT also has this issue

NOTE: When purchasing, e.g. "Infinite" Rounds of Ammunition for a Pistol, saving, then re-loading that profile, will result in the Numerical Value of Ammunition being lowered to the standard for that particular Weapon. Thus, every time the player buys "infinite" ammunition for a weapon, save, then re-load, they won't have that "infinite" ammunition from before.
-Also the fandom wiki