In ubuntu 16.04 with AMD GPU Pro drivers running on a RX 580 8GB.
1 HDMI + 2 DP (3 monitors without hub) works fine. Plug in the Hub into the 3rd DP nothing in the MST Hub. it still runs fine.
Plug a HDMI to DP cable from the monitor to the hub for the remaining 3 monitors. As soon as i plug the first monitor in it detects it, but only allows 1024×768, also unknown is named on it and does not display anyout put on the monitor. Also it lags / locks up for a good minute.
Plug in another monitor and it just craps out to black screen. Did a variation of boots with all of them plugged into the MST HUB, and so on. No joy.