Issue: 

I gave a zombie (also tried the other undead like skeletons etc.) the instant health effect through the /effect command and it was unaffected by it.  The particles appeared but it took no damage, I even made sure by punching it but it took the same amount of punches to kill as if it was undamaged. I gave it all sorts of different amplifiers of the instant health command all the way from 0 to 255 but none worked. The instant health potions and arrows still work on the zombies it is only the command effect that doesn't do anything when I believe that it should. 

Side note:

I did look up the issue already and I know the issue is already posted here but the one I saw was an older post and was based off an older version so I wanted to re-upload the issue since it would be nice to resolve this issue for the map I'm making.