If a Doc Gen license assignment does not persist for only one user, check whether the user already has an Apsona account in another organization with the same username and email address. In the reported case, the affected user already had an Apsona account in another organization using the same credentials, which prevented the Doc Gen license assignment from being successfully updated.
To resolve the issue, the customer's username was changed in the other organization to eliminate the duplicate account information. After the change, the Doc Gen license assignment persisted successfully in the customer's organization.