A possible reason is maybe you are not using the "queue" right now.

If you use the shortcut button at the top right, it lets you add a note and it doesn't ask if you want to queue the patient. 

This is to let doctors like yourself add notes quickly EVEN if the patient did not visit you in the clinic, say they just made a phone call to you.

If you go to the Queue, then add the patient there, the patient will be in the census as that's the way we can count outpatients.