Why my nrf Connect can't find my PPK device?

I want to use PPK2 to test the power consumption of my user device, I have connected the PPK device to my pc with USB cable and turned on its power switch, but when I opened the Power Profile in NRF Connect, it could not recognize the device,.Also, I noticed that my DK board now doesn't recognize Programmer, and I can actually use JLink Flasher to burn firmware, so what happened?  why?