Entity AI & Goals Mob Select Option Automatically Switching back to Custom Mobs and saying undefined sometimes.

When I Load Run Client and go back into the mob AI and goals it switches all the selected entities that i have selected for that mob to attack back to attacking itself and when i open up the mob list it labels all the mobs that isn't my custom mobs as "undefined". Help?

Before:

After:

The 'undefined' error:

 If Somebody could solve this it would be very helpful

Thank you.