I'm not sure why I have registrants showing as Will Not Attend after they purchased tickets through online sales.
This is working as intended. If I buy a ticket for someone else, I show up as their host, and since I didn't register myself, I'm marked as Will Not Attend. This is intended because that person (the host) only paid for someone else to attend the event, and is not attending the event themselves. Thus, the Will Not Attend.