Ceres New Zealand manager Bernie de Vere (above) said he was unable to comment on the litigation because it was before the courts.
The firm bought the 37 apartments from each owner, which included former prime minister and current United Nations leader candidate Helen Clark.
An IAG spokesman said NZI had paid out the indemnity value of the claim, along with amounts according to policy entitlements, to the original unit holders.
But dispute remained with Ceres, he said.
"The policy in place at the time of the earthquakes stipulates a maximum sum insured amount but the new owners, working through international insurance recovery firm Risk Worldwide, are seeking a settlement that is several multiples of that amount. So yes, there is a clear disagreement which is leading to delay in final settlement of the claim."
The spokesman said NZI did not know when it would be heard by the courts.
"We are disappointed that the path of litigation is being taken as it is now in the hands
of the court timetable to progress conclusion of this claim."
The 1920s neo-Gothic-style stone building originally housed the teachers' college before it was converted into apartments.