Hi Bernard Jurlina,
Thanks for contacting Syncfusion support.
We have validated your reported issue using your shared codes and screenshots. We suspect that you may missed to include CSS and Script file reference from layout page of your Areas. You know that every Areas act like a separate project. So, we must refer scripts and CSS from the shared folder with references in layout.cshtml too to render our components. Also, we need to initialize the Tab component in the script section after rendered HTML elements like below.
<script>
//Initialize Tab component
var tabObj = new ej.navigations.Tab()
tabObj.appendTo('#tab_html_markup');
</script> |
Please find the below UG help link for more reference.
Also please find the below getting started link to refer the CSS in the layout page.
If you face the issue still even referred the CSS and scripts properly, kindly get back to us with details to reproduce the issue in our end, that will help to address your issues quickly.
Regards,
Arun P.