I think you've misinterpreted the issue with the vibration haha. It's the switch that is being weird. When switched from loud to vibrate the phone doesn't do the vibration notifying you, but when switching from vibrate to loud it does vibrate to notify you of the switch. My phone does it too. Sometimes after like 3-4 switches it fixes itself. The actual notifications from the phone in the respective modes (vibrate or ring) are unaffected.