Hi dyh and suda,
I was able to replicate this problem. The key phrase in the dfu-util -l output is:
Cannot open DFU device 2b04:d006
That’s another device - not a Core or Photon. I used Zadig and scanned all device to discover it was my machine’s (brand new Dell, Windows 10) Bluetooth controller. Why it is in DFU-mode, I have no idea, but I was able to hardware disable Bluetooth and that removed the item from the DFU-util -l list and allowed for a successful “particle update”.
In my opinion, the actual problem lies in “Particle Update”… it’s seems to be trying to update any connected device in DFU mode and errors out when it can’t and therefore ignores my connected Core/Photon. Instead, “Particle Update” should verify that the connected DFU device is actually a Core/Photon before trying to update its firmware. That will prevent erroring out on non-Particle devices… and most importantly allow me to fully use the Patricle CLI and my Bluetooth controller. Oh yes, and prevent others from running into this same problem. 
best, Yogi