Hi,

just tested it on 4.3 (which should be pretty much the same as 4.2 regarding the App Locking) and all works fine for me.

  1. Installed AMS from Google Play.
  2. Went to App Locking and locked random app, AMS asked for a new PIN which I entered.
  3. Went out of AMS and tried to run the random app, PIN dialog appeared.
  4. Pulled down the notification bar, selected AMS which appeared instead of the PIN dialog.
  5. Pressed back, the PIN dialog appeared again instead of the random app.

What phone exactly do you have?

Filip