Alarm Triggered

I need help asap.  I had an alarm triggered yesterday and the authorities were called out to our property, we do not live at this property, it is 150 miles away from where we live.  The police reported no sign of forced entry or vandalism.  Our neighbors were able to go after the police and check inside, nothing was found.  These messages are from my Timeline and indicate the sequence of events that lead to the alarm.  It does not make sense to me?  The first alert is "Sensor added"???  No one was at the property, no one was interacting with the system.  Did it malfunction?  By the way I called tech support and they told me they could not help me and told me to call monitoring, monitoring told me they could not help me.  The sequence of events begins at the bottom, those 4 events happened all at 2:58, except when the alarm was triggered at 2:59PM, we have the door lock, it never signaled that it was open.

Alarm Triggered
Front Door 2 Entry Sensor
2:59 PM

Entry Delay Triggered
Front Door 2
2:58 PM

Entry Sensor Synced
Front Door 2 Entry Sensor synced with Smart Lock
2:58 PM

Sensor Added
Front Door 2 Entry Sensor
2:58 PM