Here's a VIDEO that may help you - Client not visible even after status being active or you can also use the following instructions to solve the issue.
1. Go to "Appointments" located on the left menu.
2. Click "Add Appointment" found on the top right, then select your client and service type and save.
If there is an error then follow these next instructions:
1. Go to "Employees" located on the left menu.
2. Go to "First Name" and click the filter icon. Input you admin's name.
3. Go to the client with the error.
4. Click "edit" and remove the client by click on the left pointed arrow, then save.
5. Now, if you go back to "Appointments" and follow steps 1 - 3 then it should work successfully.
Final Product:
