MBP 13" Retina does not recognize Asus PB278Q external monitor when connected via DisplayPort to MiniDisplayPort (Thunderbolt)

I am able to connect my monitor via HDMI but not using DisplayPort to TB. The monitor does not detect a signal and the computer does not register that a device is connected. Both ports work when using a Gigabit Ethernet to TB adapter.

I originally had the MPB connected to an old Dell VGA monitor. It worked for a week then just stopped. I was using a TB to VGA adapter. Apple Support thought it may be defective and suggested I replace it. I decided to scrap the monitor and upgrade to the Asus. I have never been able to get it to connect via DisplayPort and I have tried two cables, including one that Apple Support suggested. I have no problem when using the HDMI port on the MBP and the Monitor. Apple Support has elevated this issue to a senior tech and they are opening a case on it, but I am sure it will take some time. (we have tried the various resets and power-cyling and Asus has confirmed that my set up is correct for the Monitor).

I have the MPB vertically docked and would really prefer to use a TB port rather than have to connect an additional (and unsightly) HDMI cable each time I dock and undock the MBP. (I have tried to connect not using the dock as well, same results).

I can eliminate the wire issue (I hope) by using a TB to HDMI adapter, if it works, but I still won't get full use of the DisplayPort connection. I ordered the part, but I don't know if it will actually work in the TB port either.

Any ideas or thoughts?