Adobe Sign user set to Inactive -- how to reactivate?

Hi, in the Admin Console I added a user with a Federated Id to Adobe Sign. (In Admin Console the user shows Account Status as Active.)  The user started out as Active in Adobe Sign. The user successfully granted access to a custom application, but the next call that application made using their access token failed (unauthorized). I then checked their user in Adobe Sign and it showed as INACTIVE.  When I click on the user in Adobe Sign the only option I'm given is Edit User -- there is no Reactivate User option.  The Edit User screen does not give any option to reactivate them.

How do I reactivate the user?  Any idea why or how the user was changed to Inactive?

Thanks!
Kevin