So I've had some issues with drivedroid being unreliable booting a Toshiba laptop into tails / kali / etc. recently. The BIOS would recognise the device as connected, but just would not boot, effectively skipping the emulated CD or USB and going straight to HD or LAN.
Turns out, something has to happen to kick the USB host into action. I'm still experimenting, but if you are having similar issues, try running the nethunter custom scripts for "WLAN1 monitor mode", Y-Cable Charging, or wifite... you don't have to have an external wifi connected, just run the script.
It will of course fail. But, try drivedroid after doing this and you might find it works, as it did for me.