I found a solution!! If you hold down on the "Sound" icon that turns on silent mode, you can then set the Ringtone and Notification Sound as "Silent". This essentially makes your Sound mode a Silent mode for all contacts and notifications. Next, if you go to edit the contacts that you want to come through, you can give them an actual ringtone or vibration.
This workaround lets the contacts of your choice sound come through but everything else will be silent. Basically: Turn on Sound mode, make your default ringtone "Silent", make the special contact's ringtone anything else.
