Hi, it seems to be a bug with Unreal - [4.7] - Defaults are zeroed out upon BP Construction - Programming & Scripting - Epic Developer Community Forums , you can comment there if you’d like, I hope this will get fixed soon.
As a workaround you have to zero out the parent’s variables (MMOModularCharacter) and override them in the child (GuyModularPC), the variables that are causing this are MaxHealth, AttackRange and AttackPower but it’s best to do it for all important variables.
It’s normal, this is because CurrentTarget is not replicated and the Details tab show server-side info. You can Eject to see client-side info.