Steps to re-create:
1. Select a user in the available list
2. Click the "Add to selection" button
3. Select a different user in the available list
4. Select the user in the selected list
5. Click the "Remove from selection" button
Expected result: Selected user is removed from the selected list
Actual result: Nothing happens. The selected user is only removed if they are selected in the available list.
Also, what is the difference between the "Clear selection" button and the "Clear all users" button?