can't open play on offline editor

In my case, I was not able to save copy to USB or load anything from it..
V7.1.1. on a Windows 10 PC

Solved it today!

Open the
-"About"
  -"About Cobalt" -> "Networking" tab -> check and see what the USB Path and letter is. (Mine is F:/ ) 

The USB drive letter has to match that path, otherwise it will not be recognized by the software. 

My optical drive occupied the F:/ letter so I had to change it..

Google how to change a drive letter on your system, and change the USB to what it needs to be.

If you plug in the USB drive while Cobalt is running, it should adjust this for you automatically.

If you plug in the USB drive while Cobalt is running, it should adjust this for you automatically.

Tried that way too, and nothing changes.. 

The problem is that it recognizes an extra backup hard drive that is connected via SATA->USB, and not the flash drive itself.. 

Flash drive is FAT32, the hard drive NTFS.