I am wondering if the DOCK DA300 works with the mDP function for two (2) U2518D Monitors? We had it working without the DOCK but since getting this new DOCK both monitors mirror each other instead of acting like an independent screen.

We have both setup like the image below and mst is on and mDP is also selected for this Win 10 machine. 

I think the issue is the DA300 but it shouldn't be as it should just be a pass-through for the video.