Then apparently NOK is not taking its own expert's advice. IMO, NOK has yet to file a FRAND action in any court. NOK has initiated actions regarding invalidity, non-essentiality, etc. but not FRAND. FRAND may have come up in these prior and on-going actions but have never been the basis of the initial filing.
If NOK chooses to initiate a FRAND action now, this is where the ITC steps in. The ITC levels the contract price negotation playing field. The ITC provides injuctive relief to IDCC that prevents NOK ability to enrich itself on IDCC IPR in the US until that FRAND action is resolved in the courts.