That message indicates that the agent is using time from an agent hours voucher. You can look at the License Overview dashboard to get some views of what the usage looks like. I haven't worked with such usage yet so I'm not sure if that is directly related to the issue. By "not capturing any traffic" are you saying the PurePath count in the agents overview is zero?
Personally I would look at the agent logs for this agent to see if any more detail is provided that might indicate an issue.
Info on the consumption model:
This might be trivial but you would be surprised how many times it is overlooked. Could you check to make sure that capture events box is checked in the web server agent mapping?
This can be done by editing the system profile -> clicking the agent group ->Agent Mapping -> there is a check box where you can enable or disable the capturing of events.