XPS 14 9440 shuts down when connected to Dell monitor via USB-C

When i connect my Dell XPS 14 9440 to a Dell monitor via USB-C the notebook is shutting down after a few seconds (until it's turning off, everything works fine and showing properly both monitors). It also won't turn on again until I unplug the monitor. Tested it with 2 different U4021QW and 2 different U3818DW with latest firmware versions. When i connect it via HDMI it's working fine. Also when i connect it to monitors from other brands (tested it with Lenovo Q27h-10).

Had contact to Dell support and got the notebook replaced to ensure it's not a hardware issue, and it didn't solve the problem. Also waited quite some time for new bios updates.. and bios updates arrived over the month since the release of the notebook. Even changelog mentioned simular issues fixed with Dell docks. However, the issue with the monitors is still there. The issue is reproduciable with Windows and Linux, which makes it quite unlikely to be a drivers issue. Pretty sure it's a firmware issue of the notebook. Dell support just stopped to reply, as they couldn't find a solution. I'm worried that they didn't even take that information to the developers, that they can fix it. Else they would have fixed it over the month with a bios update, wouldn't they? It's super simple and reliable to reproduce and it happens on all hardware of the same models.

what can i do, to get this issue fixed, any ideas?