Hello Hua,
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There is a bug report for the same in Github, you can refer to it and follow it.
ToggleSwitch doesn't issue Tapped event · Issue #7698 · microsoft/microsoft-ui-xaml (github.com)
You can also submit this issue in the Feedback Hub , so you can have direct updates to the status of the issue.
You could find the Feedback Hub in the Start Menu.
Please select Developer Platform->API Feedback as the category when you submit your request.
The related team will check the request.
Thank you.