The "Process" topics are set up with a triggering interval. If you want to trigger it to run immediately, here is how.

In a browser, navigate to the Interop Server and then Engines 

Scroll down to the list of Connections and locate the ProcessRequestsForWork connection.

If the status is 'Waiting', click the Trigger action (once).  It may take a moment for the status to change to 'Running'.  If there are zero (or few) waiting requests, you might not see the status change.  However, you will see the 'last run' timestamp change.

If the status is 'Running', allow it to complete. Once it returns to Waiting status, you can trigger it as described above.

You might be interested in this related topic: Pausing message consumption