MB Air M5 + Dell Dock WD15 + LG HDR WQHD is working but not

Hi all,

I have the following situation and am looking for advice to solve it:

MacBook Air M5 Taheo 26.X Dell Dock WD15 Monitor LG HDR WQHD

Whenever I connect the MacBook via mini display (dock) and USB-C (MacBook), I don’t get a working display. Whenever I disconnect and reconnect the mini display plug at the dock, the display works.

What is wrong and how do I get a working situation without the disconnecting/connecting "hack"?

Thanks in advance.