Have you press the button on KW board?
Copied from 5.2.3 User interface, from doc "Bluetooth® Low Energy Demo Applications User’s Guide"
After flashing the board, the sensor is put in deep sleep (all LEDs are off). To flash the board in case the sensor is put in deep
sleep, press ADVSW or RESET. Also, any attached debugger loses its connection. The application default configuration enables
low power, which disables LED support. The user can manually change the configuration and enable the LED support, otherwise
all subsequent LED behavior references shall be ignored. First press of the ADVSW button starts legacy advertising. The following
applies to platforms capable of performing Extended Advertising - which excludes QN9090/K32W061/KW35. Second press starts
extended advertising, and the third press starts periodic advertising. Another press stops the periodic advertising, and another
one stops the extended advertising as well. For FRDM-KW38 board, the default enabled low-power modes are 1 and 5. This
means that the MCU is put into VLLS2 or VLLS3 stop mode. In this mode, the LED module operation is not implemented.