By default Storemapper does not load any map pins on load when viewing on a mobile device. However we understand that this may not work for everyone. You can override this by toggling off the setting for “Limit stores displayed at map load” in the Settings > Behavior
After you toggle this setting off your widget will load all locations on desktop and on mobile as well.
If you use the old version of the Storemapper interface this setting can be found under Advanced Settings and CSS