A. Check your device's settings to ensure that the app is allowed to use background data. Go to Settings > Cellular > Scroll down to the USPS app and ensure it's enabled. This may help maintain your session.

B. Try clearing the app's cache. Go to Settings > General > iPhone Storage > USPS app > Offload App. This will remove the app but keep its documents and data. Reinstall the app to see if the issue persists.