I have a similar problem to Flash driver C90TFS Partition MK10FX512VLQ12. I'm using a MK22DX256. I've looked at the example for the MK21DX128xxx5 and have trouble with it as well. The normal flash demo checks the DFlash IFR for a value before setting up the partition. For my MCU the value does not equal 0xFFFF (I get 0xF0FF) so it skips the partitioning. If I remove the check I get an ACCERR on the partition command.
Is there something that needs to occur before setting up the partition? Everything up to that command works fine.