Elegant Themes are wonderful but Epanel does not provide an option to display or hide sidebar and footer widgets for mobile. The default is to hide so you have to figure out how you unhide them each time you use a responsive theme by Elegant.

Add this to your CSS:

/* display sidebars and footer in Nimble or Trim theme  */
@media only screen and (max-width: 767px){
#sidebar, #footer-widgets {
display: block !important;
}
}
@media only screen and (max-width: 479px){
#sidebar, #footer-widgets {
display: !important;
}
}
/* end display sidebars for Elegant themes */

Here is the support post answer for Nimble theme: Keep Widgets on Mobile Site

Above I added  !important for both and for 767 portal added #footer-widgets.