Dell Ultrasharp U2412M now having issues with HDMI to DVI

[Max Power]

Hi there!
I know I'm not the first person to have problems with this setup, but I have a few guesses and wanted to ask if anyone knows about it.
In the past I have used the monitor without any problems with a Dell Latitude E6230 (i5 3rd Gen; Intel HD 4000) via its HDMI socket with a connected HDMI cable and a HDMI to DVI converter.
Now I have a Dell XPS 13 9350 (i5 6th Gen; Intel HD 520) and when using the HDMI connector of a noname USB C dock, I only have a black screen, but the monitor reacts during booting because it switches back and forth from "No Backlight-Black" to "Backlight-Black" and finally shows that no DVI cable is connected.
The same thing happened when testing with another, relatively new laptop (i7 7th Gen; Intel HD 630). Both via the USB c-dock and via the built-in HDMI port.
When testing with another monitor via DVI, there was also no picture with either laptop, but it was indicated that the frequency was not supported.
However, HDMI to DVI worked fine on an older laptop (i7 4th Gen; Intel HD 4600).
Except for the Dell Latitude, with which it used to run without problems, all notebooks have a native resolution of 1080p.
I set a different 16:10 resolution (1280x800) (Dell monitor is 16:10) on the XPS 13 for the built-in display, but that didn't change anything
The HDMI-to-DVI adapter has 24 thin and one wide pin.
For the HD 520 of the XPS 13 I only had the option to chose between 59 and 60 Hertz, which also made no differrence.
So I guess it's because of the different HDMI versions that support the different graphics cards of the laptops. Is this possible and does anyone know a workaround?
Thanks a lot

[Max Power]

Has really nobody an idea on how to fix this?

[ahuckphin]

It sounds to me like a problem with the USB-C dock.