Has any group had to proceed with site allocation despite a lack of cooperation from landowners?

We are proposing to allocate sites for useful things such as retirement housing and a new health centre. We have clear needs, evidence and consultation support. There are suitable, available sites, but their owners are just not interested in discussing it with us, even though it would be profitable enough. They clearly are holding out for more lucrative market housing.
I know that ideally we should have their agreement to submit the plan However, if landowners are allowed to derail NDPs just by playing the waiting game for more profit, it seems to make a mockery of the whole principle of neighbourhood planning - not to mention all the support and evidence we've had to provide, when they need none.
Has anybody encountered such a problem, and how have you addressed it?
We've looked at the published NDPs but their site allocations all seem to be for housing, which would be more attractive to landowners!