There's an explanation on
INZ's eVisa page. They claim that you should have no problem.
If there is an error in the visa details listed in your eVisa label, contact Immigration New Zealand (INZ) immediately. For example if your name or your passport number is wrong.
If your personal details in the eVisa do not match your passport, you may be delayed when travelling to New Zealand.
eVisa will only capture your first and last name. Middle names are not always included. As long as the names that do appear are correct, the missing names do not affect the integrity of the visa or the ability to travel to (or remain in) New Zealand.