Yes it's probably correct. To use Iberia+ you need to activate it by earning something; to transfer into Iberia you have to be both have and activated account AND it has 90 days old at least.
Activating is relatively easy, apart from flights you can credit a hotel stay or car hire, the list is on the Iberia Plus Partners page. Or you can buy some Avios.
But the 90 days is what it is, so it's best to get an Iberia account open just on the off chance that you have a future need. Now I'm guessing you have actually transferred the Chase points over, and presumably you can see them in your account, but I suspect the agent is correct that these Avios may not be available to use. You may want to ensure the account has a credit of some description other than a transfer, just to ensure that is not your next blocker (or perhaps only blocker...)
Some more experiences, albeit from BA, here:
Activating Iberia Plus account in order to transfer BA Avios