Hello Paolo, thanks for your purchase.
The options you are trying not works on the data-plugin-sticky (works only for the header sticky).
For the data-plugin-sticky you have onlye two options:
PluginSticky.defaults = {
minWidth: 991,
activeClass: 'sticky-active'
};
In your case the default option “minWidth” are being applyed and beacuse of that it´s not stick on mobile. Try changing your nav-secondary code to:
<aside class="nav-secondary" id="navSecondary" data-plugin-sticky data-plugin-options="{'minWidth': 0}">
Please try that and let us know if you need further assistance.
Kind Regards,
Rodrigo.