If you have a reservation in your booking engine that is not showing up in Check-in Scan, you should check whether the corresponding iCal for that engine is active and up to date.
To do this, go to the web control panel (https://app.checkinscan.com/client/login) and navigate to the section Properties / Edit / iCals.
There, you will see the iCals associated with the property in question and will be able to activate and update them so that the reservations are imported correctly.
