This is what I do, and it works fine everytime:
1. Get into the game, you know, where you can actually move your character around.
2. Alt-Tab to get to the trainer
3. CLICK to activate the trainer. It will say "Please wait...trainer activated"
4. CLICK ALL the cheats you want to enable i.e. click the toggle switch for Unlimited Health etc.
5. Alt tab back to the game.
6. Have fun with the cheats.
I will go and give it a try with clicking the options using the mouse instead of use the keyboard, cheers for the suggestion.
Could I ask are you using the Rockstar Launcher or the Epic Games one?
All the Best
You can just alt tab out & use your mouse to activate trainer (at the botom of the trainer) & use your mouse to activate options, that's how I do it
Sorry saw someone posted solution before me, (hadn't refreshed browser)
[Edited by StackOverflow, 11/9/2019 8:15:02 AM]
I've tried it as well and had those three files try to save. I didn't save them because I didn't know what they were but noticed that they only seemed to try to save when I tried to add things like satchels or weapons. If I just changed stats, money or even the map they didn't show when saving.
Can confirm stamina is very hit and miss. It seems to work for a while, but then some cutscene might happen, and then it doesn't. Or it might not work at all. I have tried toggling it but it didnt help.
Glad you got it working overall though 🙂