Open "Client Search" by pressing the new tab icon located next to the "Adviser Home" tab.
For the field on the left-hand side called "Status", make sure 'Hidden Only' is selected.
Press Search and you will obtain a list of all the hidden clients.
Note: You can also type in the name of the client if you are looking for a specific client. Select 'All' in the "Status" field if you want to see hidden and active clients.