1. Temporary closure of a merchant: Some merchants may be closed during school vacations, which may result in a failure to display the merchant number on your card. This may be due to reasons such as merchant personnel being on vacation or merchant business strategies. You will need to wait until the school vacation is over and the merchant reopens to display it properly.

2. Meal card system updates: Sometimes the meal card system is updated or maintained during school vacations. This may cause some merchant number information to be temporarily unavailable. Generally, the merchant number information will be redisplayed after the system update or maintenance is completed.

3. Merchant termination or replacement: Sometimes during school vacations, the relationship between the school and certain merchants may change, resulting in the termination or replacement of the merchant. In this case, the merchant number information will be removed or changed, making it impossible to display. You will need to wait until the new merchant partnership is finalized before the merchant number information can be displayed again.

It is important to note that the exact cause may vary depending on the school and meal card system. If you encounter this situation, it is recommended that you contact your school's department or the Meal Card Service Center for an accurate explanation and assistance.