If this is occuring please check the following.
Select Menu > Settings> Delay >Exit Delay. The default Exit Delay count down is set to 40 seconds. You can change the exit delay count down to however many seconds you need to exit your home or small office. Select the check mark when you have made the changes.
You can now select the Entry Delay. The default Entry Delay count down is set to 30 seconds. You can change the entry delay the same way you changed the Exit Delay.
Senerio 1: If for example the default Exit Delay (40 seconds) and Entry Delay (30 seconds) have not been changed and you armed the alarm, then triggered a door sensor by opening it immediately after arming the alarm, in otherwards you did not allow the Exit Delay to count down, therefore allowing the Alarm Panel to fully arm itself, nothing would happen. However if you then closed the door and opened the door, triggering the door sensor, the Entry delay would count down 30 seconds and the alarm would then sound. You would select Disarm to turn off the siren. To clear the Message on the Panel ie: Zone 01 Door/Window Open, close the door and then select 'Disarm' on the alarm panel
Senerio 2: If for example the default Exit Delay (40 seconds) and Entry Delay (30 seconds) have not been changed and you armed the alarm, then waited for the alarm panel Exit Delay to count down the 40 seconds, then you opened the door and triggering the door sensor, the Entry delay would count down 30 seconds and the alarm would then sound. You would then select Disarm to turn off the siren. To clear the Message on the Panel ie: Zone 01 Door/Window Open, you can do so by closing the door and it will change to a green color with a Shield Icon.
Even when the alarm is disarmed and you open the door, you should see an orange message on the alarm panel ie: Zone 01 Door/Window Open. If you do not see this then this option may have been turned off. To turn it back on go to Menu> Settings> Switch> Door/Window Open Warning> select the white/grey squares to turn it on (green) then select the check mar to save. Now go back to the main menu and open the door. You should now see the open door warning.
So as you can now see this is why you may think that the triggered sensor is taking so long to activate the alarm panel siren or wireless siren. The sensor was triggered before the Exit delay was allowed to count down and/or the Exit Delay and Entry Delay count down defaults have not been changed to a lower number.
You can also check out these KB articles:
OSI ALARM (with Display): What do the different "Zone Attributes" mean? (also called "Mode" on Alarm Display) This article also has how to set a sensor and set off the alarm immediately with no countdown delay. The alarm siren will sound as soon as the sensor is triggered.
How to change the Exit & Entry Delay time on the Smart Life app
How to change the Exit & Entry Delay time on the OSI Alarm Display