Check if SaveMyTime is active. There should be SaveMyTime notification in status bar. If you can’t find it, then application was closed by the operating system. You can activate it again by visiting the app. If there is notification from SaveMyTime but lock screen doesn’t show up just send us quick message at firstname.lastname@example.org
To prevent Xiaomi from closing down SaveMyTime you need to go to the view of currently running aplications. Then find SaveMyTime application and swipe it down. Small lock will appear in top right corner. This little trick will prevent MIUI from closing SaveMyTime in he future.