You can try this workaround:https://r2.community.samsung.com/t5/Galaxy-S/Secure-folder-notifications-hide-show/td-p/6394195 

An other way:First, go to Settings of Secure Folder -> Notification and data -> turn on Show content option.Second, install and open QuickShortcutMaker app, in Activities tab search "Settings", expand it and choose first activity that end with '...Se...