AJAX加载HTML块后jQuery动画失效问题求助

通过AJAX动态加载HTML块后，jQuery动画无法正常工作；但直接手动添加该HTML块时所有功能均正常。经排查发现，点击input元素时，无法为其添加focused、is-focused类。

图1：强制添加HTML块后的正常效果

图2：AJAX加载后的异常效果

相关代码 #

<html>
<div class="container-fluid py-4 contents"></div>
<script src="../assets/js/core/popper.min.js"></script>
<script src="../assets/js/core/bootstrap.min.js"></script>
<script src="../assets/js/material-dashboard.min.js?v=3.1.0"></script>
<script src="../assets/js/plugins/perfect-scrollbar.min.js"></script>
<script src="../assets/js/plugins/smooth-scrollbar.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
<script src="../assets/js/plugins/chartjs.min.js"></script>
<!-- Github buttons -->
<script async defer src="https://buttons.github.io/buttons.js"></script>
<script>
async function Send_ajax(data,dataType,url){
    var result ="";
    try {
        $.ajax({
            url:url, //url  (action_ajax_form.php)
            type:"POST",
            async:false,
            data:data,  
            dataType: dataType, 
            success:function(data){ 
                result = data;
            },
            error: function(response) { // Данные не отправлены
                result= response;
            }
        });
    } catch(error) {
        // handle error, set some error state, display error toast, etc...
        result= error;
    }
    return result;
}
$(document).ready(function(){
    Send_ajax("","html","../php/admin/get_config_form.php").then((result) => {
        $(".contents").html(result);
    });
});
</script>
</html>

内容的提问来源于stack exchange，提问作者Artem