This example works fine.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>jQuery EasyUI Demo</title>
<link rel="stylesheet" type="text/css" href="https://www.jeasyui.com/easyui/themes/default/easyui.css">
<link rel="stylesheet" type="text/css" href="https://www.jeasyui.com/easyui/themes/icon.css">
<script type="text/javascript" src="https://www.jeasyui.com/easyui/jquery.min.js"></script>
<script type="text/javascript" src="https://www.jeasyui.com/easyui/jquery.easyui.min.js"></script>
<script>
$(function () {
$(".tt").tooltip({
trackMouse: true, content: 'test', zIndex: 99999
});
})
</script>
</head>
<body>
<p><span class="tt">Tooltip1</span></p>
<p><span class="tt">Tooltip2</span></p>
<p><span class="tt">Tooltip3</span></p>
</body>
</html>
If your issue continues, please show an example to demonstrate your issue.