OK figured it out! I used shield and whenever I pressed numpad 1 to activate shield or even keyboard numeric 1, it would activate the shield but not the infinite health. I did take hit at least once and then used the option but with the shield it would disable the option.
Only when I stopped purchasing shield and just went ahead and took damage and then activated it would it function properly.
Have you tried to add the trainer work folder to exclusions in your antivirus? C:\Users\*username*\Cheathappens\Work\Runtime