There is currently no way to send a workout from one of the garmin training plans (i.e. W01D02 Intervals of Marathon Level I or II, etc.) directly to the device. In order to complete this action, I have to recreate the workout in the workouts section.
When I try to "send workouts to device" I get a dialog box telling me that it is "waiting to connect to device", but the device is clearly connected and syncs via Garmin Express with no problem.