Dell Precision 3551 Thunderbolt not working properly

Hello,

I have a very odd problem. I'm using a Dell Precision 3551 (i7-10750H version in case it's relevant information) with a Dell WD19S docking station and two WQHD (2560x1440) DisplayPort 1.2/HDMI 1.4 monitors, namely Dell P2418D and Philips 275E2FAE. One of them works in native resolution, while the other can only go up to 1920x1080 with weird image vibration/shaking (not flickering). This would somewhat correspond to the chart on WD19S' support page, as it suggests (I think - it doesn't even mention lower versions) DisplayPort 1.4/HDMI 2.0 is required for two monitors running in 2560x1440, BUT when I plug the dock in my other computer, a Huawei Matebook 14 2020 AMD, it runs both monitors in 2560x1440, full 60Hz, it's even capable of going higher with the refresh rate on one of them (one monitor supports it). So that makes me think it's not the issue with the docking station's or the cable's throughput potential, which could result in the setup's lack of HBR compliance, rather something peculiar is up with my laptop's port. My Precision 3551 workstation's USB-C port is supposed to support the HBR3-compliant Thunderbolt 3, which should be easily capable of running both my monitors in their native resolutions. I've tried all cable setups (HDMI and DisplayPort), updating the firmware of the dock, updating everything on my computer through Dell Command, tuning the BIOS settings to the ones recommended for using WD19S (apart from the "Browse to Dell Type-C Dock Configuration and select Always Allow Dell Docks." point, as there is no such position in my BIOS), but to no avail. I don't possess much knowledge on how Thunderbolt/DisplayPort lanes work and I'm kind of lost here. Do any of you have a clue as to what might be going on here, why one laptop is okay to run this and the other is not? Any help or suggestions will be very much appreciated.