Hi Joshua,
I bought these 2 HDMI cables. https://www.amazon.ca/gp/product/B098X5BH3W/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1
When my two monitors connect to your dock using these two HDMI cables, they both say no signal. I even tried auto source, reset SMC, reset NVRAM, nothing helps no matter what I do. However, if they connect to my macbook directly using these two cables, then I get 4k@60hz. Not sure what’s going on here. Anyway, since I get black screen when using HDMI cables connect to your dock, I’m back to display port cable now. 
pretty sad…