Using the vCO Client, with "Run" selected in the drop-down box and "Home" selected in the left navigation pane, Click "Waiting for Input" in the right-pane of the client .... Can you see and answer the workflow inputs there? I suspect that maybe even there you won't be able to 
This is a bug that was introduced with the 5.x version of vCO and introduction of the integration with the vSphere Web Client. I expect to see this resolved in the next major release of vCO.