Information about this traffic is nested deeper in Network tab.
Using Chrome 58+, you will see
entry about connection to the websocket, on the main Network tab listing.
This change a protocol (HTTP status 101),
so
every possible next request being websocket traffic, will be visible under Frames tab of above entry.
Of course you can have more opened connections to different websockets, aggregated on the main "Network" tab by websocket type.