I use LPC54608 as microprocessor and MCUXpresso as IDE.. I use JLINK tool to download code into my target. The problem I can't program external flash memory, The internal memory is corrected programmed but none location of external memory has been programmed. If I use JLINK with a line command tool from SEGGER I am able to program all memories of my board so I suppose there is no problem from JLINK.
I don't know the reason of this problem, It also happen with the last version of MCUXpresso IDE