Not all schools update their AADSAS. I was actually invited to an interview for my state school and it still hasn't shown up on AADSAS yet - it just says "Under Review," so don't depend too much on the AADSAS portal because chances are, it's behind.
When did you mail out, and to which schools? Some of the schools, like NYU and BU, to name a few that I'm familiar with, have very long application cycles. They might like you as an applicant but have kept your file on hold to compare to other applications they'll get later in the cycle. Around this time, most pre-December interview invites are already filled, but that doesn't mean you can't contact the school and ask about the status of your application.
The most important thing is not to worry - they probably have all your information and it's just a slow processing time. You'll get your invites eventually! Best of luck 🙂