How is the number of GitLab members calculated on the upgrade screen?

On the billings and on the new subscriptions screen, the number of members or “seats currently in use” is listed as 13.

When I count up all the members of our groups and subgroups, I get to 8 (7 active, 1 pending).

I know the usage count is performed once a day, but only 1 user has been removed in the last 24 hours, so at most it should show a sum of 9.

Where does the 13 come from? Can I view the list of members it consists of anywhere?