If you look at the C51 tab in the project options( Options for Target 'Target 1') , you will see that there is a preprocessor symbol"NO_RENUM" has been defined. This causes FX2LP to not undergo renumeration once the firmware(vend_ax in this case) is downloaded. Unless the device renumerates, it will not be recognized with the new set of descriptors. A vendor command "a8" has been defined in vend_ax.c which will cause FX2LP to renumerate. Hence, if you issue the vendor command "a8" from CyConsole or Control Centre, you will be able to see FX2LP renumerate with the new set of descriptors. Another option is to remove the NO_RENUM directive from the C51 tab .