Authorized User accounts in FICO scoring

[Anonymous]

Are AU accounts included in the calculation of Average Age of Accounts in FICO?

What about revolving AU accounts with a zero balance?

I recently observed a 14 point FICO 8 score drop where the only "visible" event was a very old AU account (much older than the others) going from $100 to zero balance, and I was wondering if that might be the explanation (i.e., by going to zero the AU account was now exluded from AAoA) or whether I should keep looking for the cause.

[Azza]

I am an AU for my wife's Discover It. Experian figures it into my utilization while Equifax and Transunion see it but don't factor it in.