Due to a limitation of the Sierra API, each User must have a Sierra Agent Profile, as well as a Lead assigned to them in Sierra, before they can be enabled in the Manage Users page of the CBX.
Setup Sierra Agent Profile:
On the Sierra Interactive home page click Users in the navigation bar and select Users from the dropdown menu:
Next, click the + icon in the Agent Profile column row for a given User:
Click Save and Exit:
Finally, refresh your CBX Manage Users page to see the added User:
Note: a Lead must be assigned to an Agent in Sierra before the Agent will appear on the Manage Users page of your CBX.