it was something along the lines of
DECLARE_DYNAMIC_MULTICAST_DELEGATE_SevenParams(FOnHealthChangedSignature, UTPSHealthComponent*, OwningHealthComp, float, Health, float, HealthDelta, FDamageEvent const&, DamageEvent, const class UDamageType*, DamageType, class AController*, InstigatedBy, AActor*, DamageCauser);
but that just messsed everything else up.
I also have this:
// in my TPSCharacter.cpp
HealthComponent->OnHealthChanged.AddDynamic(this, &ATPSCharacter::OnHealthChanged);
this would fail compilation too when i had the SevenParams in my delegate