I've built a Room Reservation app, and one of the features allows you to view your Calendar (using Outlook as a connector). Oddly enough, when I 'play' the app for the first time, I click "Calendar", this error comes up and no events are populated in my calendar:


...and once I go back to the main screen and re-click on Calendar, it populates my Calendar and no error is thrown:

This issue does not exist when my app is in Edit mode. When I click on Calendar for the first time when in Edit mode, everything loads as desired and no error is thrown.
Here is the code for my 'Items' property of the calendar events:

Would anybody know the cause behind the calendar failing to load the first time (when in 'play mode'), but working every time after?