Restart the trainwell app on your iPhone
Edited
If you're encountering an app error, in some cases it can help to force close the app (quit) and reopen the app in order to refresh the app.
Here's how:
From the home screen of your iPhone, swipe up from the bottom of the screen and pause/hold in the middle of the screen
This will open the "App Switcher" and you should see all apps currently open on your device by swiping left or right
*If you have an iPhone with a Home button, double click the home button
Swipe to find the app that you want to close, then swipe up on the app's preview to close the app
Apple Support
🔗 Quit and reopen an app on iPhone