I am a PhD biotechnology, just started work in Otago University as researcher (breast cancer). My contract is for more than 2 years.
I had my ITA submitted before I got the job offer, and once I submitted the job offer my residence was immediately approved.
If you have those rolling contracts, do you have any inkling if a new contract is likely for you? If so, you could show that you will have continued employment, albeit on different contracts. Or indeed HR or other powers in the uni may be able to help convince INZ that your employment is contract-based, but repeatedly renewed