I have a Dell Latitude 7480 connected to my 3-monitor Plugable USB-C device. This generally works great, but every couple of days I sit down and only one of the two external monitors has an image; the second is looking for signal and in power-save mode. Rebooting the laptop has no effect, nor does powering off/on the problem monitor. The only fix I’ve found is to power-cycle the Plugable docking station itself. A reboot of the docking station quickly restores both monitors to working as before.
If it makes any difference, both monitors are connected to the docking station via HDMI interfaces.