Why is my calendar ticket itinerary missing?

The reasons why my calendar ticket purchase itinerary is missing are synchronization problems and calendar application problems.

1. Synchronization problem. If you use the calendar application on multiple devices, and only add a ticket purchase itinerary on one device, you will not be able to see the itinerary on the other devices.

2. There is a problem with the calendar application. If there is a problem with the mobile phone calendar application or other calendar applications, the ticket purchasing travel itinerary will disappear.