DL-6950 not supporting 60Hz display modes

[shol74]

I'm having an issue with a USB-C docking station with a DL-6950 chipset. My understanding is the 2 HDMI ports would support 60Hz refresh modes for 4k:

https://www.wavlink.com/en_us/product/UG69DK1.html

Specifically I'd like a 3840x2160 resolution with a 60Hz refresh rate, and the display supports it fine through the laptops HDMI output, but the highest modes listed for the dock are:

3840 by 2160, True Color (32bit), 24 Hertz
3840 by 2160, True Color (32bit), 25 Hertz
3840 by 2160, True Color (32bit), 30 Hertz
4096 by 2160, True Color (32bit), 24 Hertz
4096 by 2160, True Color (32bit), 25 Hertz
4096 by 2160, True Color (32bit), 30 Hertz

I'm on Win10 Pro v.1803. I've tried DisplayLink driver version 8.2.1952.0 (5/22/2017), an 8.4 version (dated Nov I think), and the latest 8.5.3459.0 (5/11/2018).

Here are the device IDs:
USB\VID_17E9&PID_6000&REV_3106&MI_00
USB\VID_17E9&PID_6000&MI_00