Solve this by replacing UProperty with FProperty like this:
auto Property = FindFieldChecked<FProperty>(UAttributeSetBase::StaticClass(),
GET_MEMBER_NAME_CHECKED(UAttributeSetBase, Health));
auto Property2 = Data.EvaluatedData.Attribute.GetUProperty();
if (Property == Property2)
{
UE_LOG(LogTemp, Warning, TEXT("Health: %f"), Health.GetCurrentValue());
}