This was an issue for me and left me scratching my head for several hours, until I realized my mods were not working due to something with the rockstar launcher. Your last step is to download and install this modified launcher. This launcher prevents GTA V from accessing the internet, which prevents any interference with mods. You can install menyoo by drag dropping all the files in the archive into your GTA V folder. How do you install Script Hook? it's as simple as downloading the archive, opening it, opening the folder within called 'bin' and dragging and dropping the three files into your GTA V folder. Head to this page and install Script Hook V. Make a duplicate of your GTA V installation by copy and pasting the folder it's in to anywhere else on your computer. It is important for future steps in the tutorial, which will entail modding your GTA V.
This step is optional but HIGHLY RECOMMENDED that you follow it.
That is simple my dear, follow these prescribed steps exactly: