Script to Cancel Task is not working in CRM 2016

Hello,

We have a custom button to cancel Task. It used to work in CRM 2013 but after we upgraded to CRM 2016 it's not working anymore. Clicking the button will not do anything - no error message, etc.

Below is my script - is there anything different that's not supported in 2016 causing this not to work?

function cancelTaskRecord(RECORD_ID) {
    //set Task record to Cancel status, then force to close the page
    Xrm.Page.data.save().then(changeRecordStatus(RECORD_ID, 2, 6), Xrm.Page.ui.close());
}

function changeRecordStatus(RECORD_ID, stateCode, statusCode)
    {
    // create the SetState request
    var request = "<s:Envelope xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope/\">";
    request += "<s:Body>";
    request += "<Execute xmlns=\"http://schemas.microsoft.com/xrm/2011/Contracts/Services\" xmlns:i=\"http://www.w3.org/2001/XMLSchema-instance\">";
    request += "<request i:type=\"b:SetStateRequest\" xmlns:a=\"http://schemas.microsoft.com/xrm/2011/Contracts\" xmlns:b=\"http://schemas.microsoft.com/crm/2011/Contracts\">";
    request += "<a:Parameters xmlns:c=\"http://schemas.datacontract.org/2004/07/System.Collections.Generic\">";
    request += "<a:KeyValuePairOfstringanyType>";
    request += "<c:key>EntityMoniker</c:key>";
    request += "<c:value i:type=\"a:EntityReference\">";
    request += "<a:Id>" + RECORD_ID + "</a:Id>";
    request += "<a:LogicalName>task</a:LogicalName>";
    request += "<a:Name i:nil=\"true\" />";
    request += "</c:value>";
    request += "</a:KeyValuePairOfstringanyType>";
    request += "<a:KeyValuePairOfstringanyType>";
    request += "<c:key>State</c:key>";
    request += "<c:value i:type=\"a:OptionSetValue\">";
    request += "<a:Value>" + stateCode + "</a:Value>";
    request += "</c:value>";
    request += "</a:KeyValuePairOfstringanyType>";
    request += "<a:KeyValuePairOfstringanyType>";
    request += "<c:key>Status</c:key>";
    request += "<c:value i:type=\"a:OptionSetValue\">";
    request += "<a:Value>" + statusCode + "</a:Value>";
    request += "</c:value>";
    request += "</a:KeyValuePairOfstringanyType>";
    request += "</a:Parameters>";
    request += "<a:RequestId i:nil=\"true\" />";
    request += "<a:RequestName>SetState</a:RequestName>";
    request += "</request>";
    request += "</Execute>";
    request += "</s:Body>";
    request += "</s:Envelope>";

    //send set state request
    $.ajax({
        type: "POST",
        contentType: "text/xml; charset=utf-8",
        datatype: "xml",
        url: Xrm.Page.context.getClientUrl() + "/XRMServices/2011/Organization.svc/web",
        data: request,
        beforeSend: function (XMLHttpRequest) {
            XMLHttpRequest.setRequestHeader("Accept", "application/xml, text/xml, */*");
            XMLHttpRequest.setRequestHeader("SOAPAction", "http://schemas.microsoft.com/xrm/2011/Contracts/Services/IOrganizationService/Execute");
        },
        success: function (data, textStatus, XmlHttpRequest) {
            Xrm.Page.ui.close();
        },
        error: function (XMLHttpRequest, textStatus, errorThrown) {
            alert(errorThrown);
        }
    });

}