I'm having the same issue with my 920. I'm running the latest build but the battery is draining so fast I decided to rollback to 8.1 and have my precious 920 back in the "normal" state.
Here's the rub. If I connect the phone to my main PC, WPRT finds it, and everything goes well right up until the flash. Then my phone dies and goes into black screen/no vibration/damaged bootloader. I tried a very elaborate rescue operation found
here but my PC fails every time. My Asus VivoTab saves the day and flashes in the first go.
That happened with the previous build. With the current build I have no desire to destroy my phone first, so I connected it to my tablet immediately and ran WPRT. The program finds the phone, detects that it is, in fact, 920, offers to download package. Downloads it, verifies the thing and then poof, device not found...