Ngapuhi is refuse to settle its (legitimate) Treaty grievance for anything less than the full return of all lands, even those now privately owned.
That is their right of course but it means they’ll never get a settlement – they’ll just stay in permament grievance mode.
Sucessive governments have made it very clear that they will not confiscate privately owned land to settle Treaty claims, as this will merely replace one grievance with another.
The other issue is that no settlement will or can ever be for the full amount of land once owned. To ignore the huge increases in land value due to 150+ years of modern industry is also not justifiable.
I suspect Ngapuhi are simply saying “we want it all back” as a negotiating tactic to push the Crown into a more generous offer. However the Crown has to keep mind of relatitivies with other settlements so it is constrained also.