Modal dismissal with `router.back()/dismiss/()dismissAll()` not working on real iOS devices

[minon250]

Hi Expo Team,

I'm encountering an issue with dismissing modals programmatically using router.back() in Expo Router v2 when running on a real iOS device. The same code works as expected in the iOS simulator.

Description:

When a modal is presented using the presentation: 'modal' option in _layout.js and I attempt to dismiss it from within the modal component using router.back(), the modal does not dismiss on a physical iPhone. The button press seems to register (no errors are thrown), but the navigation does not go back to the previous screen.

Steps to Reproduce:

1. Create a basic Expo Project
2. Configure a modal route in _layout.js (or _layout.tsx) with presentation: 'modal'.

   // app/_layout.tsx
   import { Stack } from 'expo-router';
   
   export default function RootLayout() {
     return (
       <Stack>
         <Stack.Screen name="index" />
         <Stack.Screen
           name="modal-screen"
           options={{ presentation: 'modal' }}
         />
       </Stack>
     );
   }
   

3. Create a modal component (app/modal-screen.js or app/modal-screen.tsx) with a button that calls router.back():

   import { useRouter } from 'expo-router';
   import { Button, View, Text } from 'react-native';
   
   export default function ModalScreen() {
     const router = useRouter();
   
     const handleDismiss = () => {
       router.back();
     };
   
     return (
       <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
         <Text>This is a modal!</Text>
         <Button title="Dismiss Modal" onPress={handleDismiss} />
       </View>
     );
   }
   

4. Navigate to the modal screen from another screen using router.push('/modal-screen').
5. On a real iOS device, press the "Dismiss Modal" button. The modal remains visible.
6. Perform the same steps in the iOS simulator. The modal is dismissed successfully.

Expected Behavior:

Tapping the "Dismiss Modal" button on a real iOS device should trigger router.back() and dismiss the modal, returning to the previous screen.

Observed Behavior:

On a real iOS device, tapping the "Dismiss Modal" button does not dismiss the modal.

Environment:

• Expo Router Version:~4.0.20
• React Native Version: 0.76.9
• Platform: iOS 18.4
• Simulator: iOS 18.4

Reproducible Demo:

I can provide a minimal reproducible example if needed. Please let me know the best way to share it.

Thank you for your time and attention to this issue.