问为什么IE 11浏览器对jQuery AJAX请求随机有内容长度=0？

EN

<filter>
    <filter-name>SecurityFilter</filter-name>
    <filter-class>waffle.servlet.NegotiateSecurityFilter</filter-class>
    <init-param>
        <param-name>principalFormat</param-name>
        <param-value>fqn</param-value>
    </init-param>
    <init-param>
        <param-name>roleFormat</param-name>
        <param-value>both</param-value>
    </init-param>
    <init-param>
        <param-name>allowGuestLogin</param-name>
        <param-value>false</param-value>
    </init-param>
    <init-param>
        <param-name>securityFilterProviders</param-name>
        <param-value>
            waffle.servlet.spi.NegotiateSecurityFilterProvider
        </param-value>
    </init-param>
    <init-param>
        <param-name>waffle.servlet.spi.NegotiateSecurityFilterProvider/protocols</param-name>
        <param-value>
            Negotiate
            NTLM
        </param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>SecurityFilter</filter-name>
    <url-pattern>/welcome.do</url-pattern>
</filter-mapping>

function getData() {
    let dashboardFilterParams=new DashboardFilterParams(<passing the arguments to this constructor>);
    //alert(JSON.stringify(dashboardFilterParams));
    //console.dir(dashboardFilterParams);
    $.ajax({
            url: str_THIS_WA_URL+"/xyz/abcdXYZ.do?httpReqType=ajaxReq",
            data: JSON.stringify(dashboardFilterParams),
            dataType: "json",
            contentType: "application/json",
            mimeType: "application/json",
            type: "POST",
            success:function(responseData){
                        if(responseData && "success"===responseData.reqResult) {
                            //populating tables & drawing charts using Google Charts JS API if successfully fetched the data
                        } else {
                            //showing error message
                        }
                    },
            error:function(data,status,er) {
                        showTheMessage("danger","Error getting data");
                        console.log("error: "+JSON.stringify(data)+"\n status: "+status+"\n er:"+er);
                    }
     });
}