DataTables添加数据后调用ajax.reload()刷新时触发无效JSON响应错误的问题求助

大家好，我在项目里用DataTables展示数据库返回的列表数据，现在遇到一个问题想请教下：

首先是页面中的表格HTML结构：

<div class="table-responsive mt-4" style="padding-top:50px;">
    <table id="memberList" class="table table-striped">
        <thead>
            <tr>
                <th>Employee Number</th>
                <th>Employee Name</th>
                <th>Designation</th>
                <th>Department</th>
                <th>Authorization</th>
                <th></th>
            </tr>
        </thead>
    </table>
</div>

然后是初始化DataTables的脚本：

$('#memberList').DataTable({
     processing: true,
     serverSide: true,
     filter: true,
     scrollY: '400px',
     orderMulti: false,
     ajax: {
         url: getMemberList,
         type: 'POST',
         datatype: 'json'
     },
     columns: [
         { data: "EmpNumber", name: "Employee Number" },
         { data: "EmployeeName", name: "Employee Name" },
         { data: "Dessignation", name: "Designation" },
         { data: "Department", name: "Department" },
         {
             data: "IsAuthorized",
             render: function (data, type, row) {
                 return data
                     ? '<span class="text-success">Allowed</span>'
                     : '<span class="text-danger">Denied</span>';
             },
             name: "Authorization"
         },
         {
             data: "EId",
             render: function (data, type, row) {
                 return `
                 <div class="btn btn-danger delete-member" data-id="${data}">
                     Remove
                 </div>`;
             },
             orderable: false
         }
     ],
     language: {
         search: "Search:"
     }
 });

页面里还有一个添加按钮，用户通过下拉框选择数据后点击添加，数据会提交到后端控制器完成业务处理并存入数据库。在请求成功的回调函数中，我尝试刷新DataTables，代码如下：

if (response.success) {
  showSuccessToast("Employee added successfully");

  // Refresh the DataTable
  $('#memberList').DataTable().ajax.reload();

  $(ctl).prop("disabled", false).text(originalText);
  closePopup();
}

但这段代码并没有生效，反而触发了错误提示：

DataTables warning: table id=memberList - Invalid JSON response.

想请教下大家这个问题该怎么解决？

备注：内容来源于stack exchange，提问作者Dev Beginner