React Native: .env file values aren't being read with react-native-config

I’m rebuilding my Expo app in pure React Native and trying to figure out the environment variable situation. I’m trying out react-native-config, currently on "^1.5.1". I installed using yarn add react-native-config and then I did npx pod-install.

Here is my .env file:

ENV_NAME=prod
TEST_ENV_VAR=hello

And for one of my components, I have code like this:

import Config from "react-native-config";

export function LoginScreen({ navigation }) {
   ...
   const [isDev, setIsDev] = React.useState(Config.ENV_NAME === 'dev')
   const [testEnvString, setTestEnvString] = useState(Config.TEST_ENV_VAR)
   ...

   return (
      ...
        {isDev ? 
        <View style={styles.row}>
            <Text>Debug info: {isDev}</Text>
            <Text>Test string: {testEnvString}</Text>
        </View>
        : null}
      ...
   )

What I’m finding is that:

• isDev always evaluates to true, ie that snippet in the return ( ) is always showing, even when the .env file has ENV_NAME=prod
• isDev does not itself show up as a value after the string "Debug info: " – so it’s some kind of value that shows up as blank but evaluates to true
• testEnvString also does not show up in the displayed component

Am I missing anything in my setup here?

Addendum: I’m testing on iOS simulator (I don’t care about Android yet) with npm start