Fastboot not showing device, adb finds it I'm having issues trying to get Fastboot to find my device. 
Interestingly ADB finds it.
My specs are below:


Computer: Ubuntu 14.04 
Phone: One Plus Two Oxygen OS 2.1.1

james@james-Aspire-3830TG:~$ adb devices
List of devices attached 
3778baee    device

james@james-Aspire-3830TG:~$ fastboot devices
james@james-Aspire-3830TG:~$
Make sure you are in fastboot mode before using fastboot devices for device to show up.

If it still does not show up, looks like you don't have the fastboot driver properly installed.

Use the  following to install fastboot drivers: 

sudo apt-get install android-tools-fastboot


If the repository isn't available add it using: sudo add-apt-repository ppa:phablet-team/tools &amp;&amp; sudo apt-get update

Note: The commands are for distributions using apt. Specifcally Ubuntu and variants. Commands for others may vary.