By default, the plugin is assuming that your buttons include both the text and the icon. On mobile, the text is hidden using a screen reader text CSS technique, so that only the icons will show. Since you are using the buttons with text, but no icons, that approach won’t work for you.
One thing you can do is to add this CSS to your theme, or the additional CSS panel in the Customizer:
span.sss-name {
position: relative !important;
}
The button labels will not be visually hidden on smaller devices with this CSS. However, because the buttons will be larger than they would be with just the icons, you may need to restyle how the buttons display on smaller devices, as the plugin styling is set to use display: table;
for the buttons container, and the buttons are display: table-cell;
, which will likely cause the buttons to overflow the parent container and may cause other issues.
With this in mind, it might be easier to consider disabling the plugin styles altogether. You can copy them from the plugin to your theme (or additional CSS panel) and modify the display properties as well as removing the screen reader text CSS altogether, so that you don’t have to override it as suggested above.