Hey guys, this is such a monstrous pain, but small silver lining -- you can at least push the image down to the switch via vManage, and as long as you don't select "Activate and Reload" it won't error out. From there you'll see the file in flash and ...

Seeing the same thing today, sandbox shows active, but no access details received.   Anybody with advice troubleshooting, or tearing down the sandbox to try again?