Long story short:
I have this dock:
https://www.x-kom.pl/p/446039-stacja...kaAk_-EALw_wcB
...and tried those cables with it:
https://www.speckable.pl/pl/product/...60-czarny-0-5m
https://www.x-kom.pl/p/675447-kabel-...w-10-gbps.html
None of them transfer any video (they only charge the laptop). The original cable included with the dock does work. Please, don't ask me why I need third-party cables instead of sticking with the OEM one. Also, don't suggest contacting the manufacturer, I've already done that and they're not very helpful ATM.
Reasons?