Polycom Group 500. Problem with content sharing by USB Type-C

Hi,
We have some Polycom Group 500 and we recently bought laptops (Dell) without hdmi ports, only usb type-c. We tried to sharing content from these laptops to our codecs using the adapter USB Type-C - HDMI. But we see only Black Screen.
Also we check it on a simple hdmi monitor, it fine displays video from laptop 

Polycom RealPrecence Group 500

sw 6.2.2-580140