I have bought Google Cardboard for my Nexus 4, but its side magnet to go inside the apps is not working. I don't know what's wrong. Can anyone help me?
In my experience it's very finicky. Try entering a cardboard app and using the center dividing line on the screen as a guide to positioning. If that still doesn't work, I usually move the phone left in very small increments until I can get it to work.
It may also depend on the manufacturer of the Cardboard set. The magnet is using the phones magnetic sensors to trigger a command. If the magnet they provided isn't strong enough or is positioned incorrectly, it won't work.