Connect Smartphone with C34J791

[wattenre]

Hi,

I tried to connect my Samsung Galaxy S10 via USB-C to USB-C cable to the thunderbolt monitor. No matters if I use the 15W port ir the 85W port, the phone is just charging. 

Why is no Video and Audio Signal transmission to the monitor possible (display sharing or dex)?

Using the USB-C Professional Dock from Asus, I can use Samsung Dex, where is there the difference?