The jQuery Validation library apparently does not clear or hide the Validation Summary list after a successful validation. If the form is valid and will be submitted to the server, it looks better to hide the list. Use a submitHandler callback to deal with this.

submitHandler.ClearValidationSummary.js

// Set the submitHandler callback via the settings object, as is necessary if you are using Unobtrusive Validation.
// If you are not using Unobtrusive Validation then you can set submitHandler in the options object passed to validate().
$("#iTrentExportForm").validate().settings.submitHandler = function (form) {
    BlockPage(); // you may want to block the page during the Ajax call
    
    var container = $(form).find("[data-valmsg-summary=true]"),
    list = container.find("ul");

    if (list && list.length) {
        list.empty();
        container.addClass("validation-summary-valid").removeClass("validation-summary-errors");
    }

    // We amended jquery.validate.js to pass on the return value of this function.
    // By returning true this should allow propagation of the submit event to continue.
    // This is dependent on the jquery.validate.submithandlerfix.js Gist
    return true;
};