If we have not added a user directly to a workplace, but have only created it in a list, then we need to assign it to a workplace.
In the list of users (Authorisation system>Users), find the desired user, highlight it and right-click to open the drop-down menu and select the Assign to workplace action:
This will open the organisation chart where you can select the desired workplace. If the user is already assigned to a workplace, this is indicated by a tick mark:
In the left corner you can see which workplace the user is assigned to.