Power Expand 13-in1 will only power 1 external monitor

I just purchased a new MacBook Pro (Intel chipset) and the Anker 13-in-1 power expand dock. I have 2, 4k monitors to attach. One is ported through the HDMI, the other is on the USB-C//T3 port on the back (next to the powered T3, which is linked to the Computer.
I used a USB-C-> DisplayPort cable.
The HDMI monitor works fine. The computer won’t see the other once connected via USB-c port.
Any suggestions?