Issue with passing a variable from UI action to UI page

[RuizheZ]

I can't seem to pass a variable from my UI action into a UI page despite following the syntax and examples. It always outputs to nothing. 

UI action: 

function processAssets() {

    var itemList = g_list.getChecked().toString();

    if (itemList) {

        var dialogClass = (typeof GlideModal !== 'undefined') ? GlideModal : GlideDialogWindow;

        var dd = new dialogClass('asset_return');

        dd.setTitle('Asset Return');

        console.log('Itemlist: ' + itemList);

        dd.setPreference('ids', itemList);

        dd.setWidth(800);

        dd.render();

    }

}

UI Page HTML: 

<g:ui_form>

<input type="hidden" id="sys_ids" name="sys_ids" value="${ids}"/>

<div style="display:flex; flex-direction: row; justify-content:center; gap: 20px" id="main">

</div>

</g:ui_form>

UI Page Client Script: 

generateBody();

function generateBody() {

    var sys_ids = gel('sys_ids').value;

    debugger;

    console.log("Here: " + sys_ids);

}