Workaround for loading issues when on cellular data mode:
- Open settings app.
- Select cellular option.
- Scroll down until you see the app having issues.
- Make sure the switch on that app is set on (green.) This allows or disables cellular service.
Note: Supposedly there was a version of iOS that disabled this option on apps that were installed on that specific version. Unloading and reloading the app remembered the setting.