If you having trouble loading Scan to Ship through the Shopify mobile app (both on iOS and Android) please update to the latest version of the Shopify mobile app through the Apple App Store of Google Play Store.
Shopify have just released a new version fixing a bug that was preventing almost all Shopify apps from loading on mobile devices.
As far as we know, accessing Scan to Ship via your Shopify admin area with a web browser is not affected.