I'm trying to invite a guest to a business class trello board. I message pops up saying "must reactivate user first" with no other explanation or link. What does this actually mean? There is no documentation about this, and poorly/loosly formatted searches lead to this page,
https://help.trello.com/article/1029-what-is-a-deactivated-user
which is talking about reactivating a member of a workspace, which is a completely different situation, as far as I can tell. The user in question has never been a member of the workspace in question, nor should they be.