Laptop: Dell Precision 5220 running Ubuntu 16.04
Docking Station: Dell (can't find any more info on it), connects with thunderbolt.
Monitors: 2x Benq Senseye 3, Model #
BIOS Version: 1.9.4
I can only ever have the machine connect to the docking station and have my external monitors work if it's restarted while plugged into the dock. If I unplug my machine for any period of time longer than a few minutes and try to reconnect, everything on the laptop freezes except mouse movement. If I click any input fields they don't select until I unplug the dock at which point they'll select properly. I can even type stuff into them but it doesn't show up until I unplug the dock where my screen snaps back into action. While able to move the mouse, I can't navigate past the boundary of my laptop screen to where the external monitors would be.
The only way to get this to work is by restarting where everything goes back to normal. As a test, I took my laptop to a co-worker's docking station (same one) while he was using it, he unplugged and plugged in my machine and the same thing happened.