Sub Menu no dropdown?

[minimallinux]

Hi, is there any setting or snippet to get the (mobile view slideout) sub items to drop down from parent.
At present sub items don't show up at all. Just don't show.
I tried adding class uk-nav-sub in menu but doesn't work?
My off-canvas menu is like below (tried original already)

'mobile', 'menu_class' => 'uk-nav uk-nav-offcanvas uk-nav-parent-icon', 'depth' => 2, 'walker' => new WordpressUikitMenuWalker('navbar'), 'echo' => false, 'fallback_cb' => false )); ?>

Is there anywhere in walker class we can enable uk-nav-sub. parent-icon, nav-parent etc or other ul classes for the dropdown in mobile to get it working properly? I would like to be able to do something (for mobile slideout) like the html one I have at

https://satisfying-stocking.surge.sh/ (resize to 320px)

To the modified wordpress one I have at

http://staging4.webmobapps.com/

There are 2 sub items in wp version above but don't show up at all in mobile view.

The html one doesn't use any jQuery or whatever (which I had to do on another theme), it just uses the built in nav classes and icon classes from UIKit, so need to get them in to the Wordpress version.

Otherwise works good.
Tips welcome.
Thanks