If you see the usage graph and data in other places in NetWorx while only the Connection Monitor window is empty, simply close the Connection Monitor window and re-open it anew.
If however you don't see the usage graph and data anywhere, please check your NetWorx settings under
Mode on the
Main tab. It needs to be set either to 'Monitoring of applications' or 'Monitoring of a network adapter'. For the latter, please ensure that the correct adapter is being monitored by clicking the Settings button next to it.
If everything is set correctly, the top item in the NetWorx taskbar popup menu can be used to open the usage graph. You can also have the current speed displayed in the taskbar by ticking the corresponding option in the popup menu.