Q: I am unable to get 4 displays working using a 4-port MST hub with an AMD or Nvidia video card. Why is this?
Not all video cards support MST, and some may not support four displays.
Please confirm with your video card manufacturer that your card supports MST and the number of displays you need.
You will also need to check the total bandwidth of connected displays.
If the resolution from the 1st display is 4K 60Hz, then all other 3 external displays will not display properly.