Unable to detect DA14580 in debug mode

Hello,
We are having our customized board using DA14580-01, we are using an external 16MHz oscillator to feed to the chip and the voltage levels as per DA14580 datasheet(1.2V peak-to-peak).
We are able to even observe 32.768Khz across XTAL32Km and XTAL32Kp.
But when we try to connect to J-Link using Keil project and enter debug mode, we are unable to see the BLE chip being detected
i.e. In Debug mode==>Settings==>Sw Device, we are unable to see any IDCODE.

Thanks
asmaitha