Alarm system - Lexus has no answers

[Jac]

Our car (23 model) was broken into at a university multi-level car park, with the passenger window smashed and the front Dashcam ripped out and stolen. 

The police report states " Vehicle fitted with an alarm that appears not to have sounded". It is however very hard to tell when they smash the window as CCTV doesn’t cover where your car was parked but shows them walking towards the car at the following times. 

Lexus scanned the alarm system and determined there was NOTHING WRONG with the alarm. 

The time frames of the incidents provided by the police and our son also triggering the alarm when security called him out to the incident do not appear on the scan. Also, no notifications were received on the app. 

There is not a single person at Lexus Brighton and Lexus Australia who can answer why there is a discrepancy between the police report, our son triggering the alarm and the scan results. 

Hoping someone here can answer my question.