Dell Latitude 5521 with docking WD19DCS cannot run two 4k monitors

Hi, we bought new Dell Latitude 5521 laptops for the company (Intel Core i7-11850H (2.5GHz, TB 4.8GHz, HyperThreading), 16GB RAM DDR4, 512GB SSD M.2 PCIe, NVIDIA GeForce MX450 2GB GDDR6) and we face a problem that we cannot run two 4k monitors in full resolution when using WD19DCS docking station. But if we connect one monitor to hdmi port so then both monitors are running 4k resolution. 

We tried when connect WD19DCS docking station to HP Zbook Fury G8 and both monitors are running 4k resolution without any problem.

Thank you for any advice.