Hi, Yin 

This might be an issue with the Time Zone settings.

Please check these points:

If you enabled this setting : Show booking slots in client time zone on the Amelia general settings :

If you enable this option your clients will see time slots in their own time zone, and once they schedule an appointment you will see it in the back-end in the time zone that you have set in the WordPress General Settings under the Timezone option. So, for example, if your clients are in a time zone that is 1 hour less than yours, they will schedule an appointment for 8 pm, and you will see this appointment at 9 pm in the appointments list.

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Also, for example, in the main WP time zone, on the settings , if you have set a fixed UTC time zone.

We strongly recommend switching to a City that is the closest to the same time zone, to avoid any issues between back-end and front-end times.

Please check out more details explained about using time zones in Amelia on this page. Time Zones with Amelia

 The main summary is : 

When you select the city you're in, in WordPress' General Settings, the system automatically calculates the Daylight Savings Time, and shifts the clock accordingly, so if you have any issues with what you see on the front-end vs what you see in the back-end, always check the Time Zone in WordPress.

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And with this new feature to set employees time zones; we also recommend picking a city, rather than a fixed UTC time zone, to avoid any issues.

Important to note : for employees as well, it will only show their time zone when they log into the employee panel;  otherwise on the back-end, it will always show your WordPress time zone.

I hope that was clear, but let me know if you fixed the issue, or if it is still persistent, please.

Thank you