This feature of Windows Phone. If the reminder or toast to send from your lock screen (even without a password), the navigation application is limited. I think that there is no way now to fix this behavior ...
I got even more unpleasant situation with reminders of the applications:
1) If screen is not locked and you gave a reminder of the application, then click on the reminder will open the application, you can immediately take action in response to the reminder. All well and good.
2) when the lock screen (even without a password) and you send a reminder of your application, there is no ability to navigate the application by clicking the reminder. Reminder, you can only cancel or postpone for a while. Then the user must unlock the screen, open the program and try to understand what to do in response to this reminder.
At least toast is displayed in the notification center, and the reminder disappears without a trace and the user attempts to find what caused the reminder.
I do not understand why such inconvenient behavior for user application communicates with the lock screen.
Wrote a post on UserVoise, but without response.
Enable to open a task or an appointment directly by tap on the reminder