User keeps disappearing from Team

I'm the administrator for my company's Articulate account and I'm having a strange issue. For background, our subscription lapsed by a few days due to a clerical error and I have to add all our users back manually.  Most are not having an issue but I keep adding a user to my Team and when she accepts the invitation, it tells her she needs to purchase a subscription and she disappears from the Team portal. Anyone have a solution for this issue?  Thanks!