ReactNative TextInput value doesn't update on IOS

Expo SDK v27.0.0 based on React-Native 0.55

I have a value I want numeric values only so I filter the input using onChangeText. On Android you see the non-numeric value but it is then erased but on IOS all characters are displayed until another digit is pressed. The code is as follows:-

state = {
    appCode: ""
};

render() {
    console.log(this.state.appCode);
    return (
        <View style={styles.container}>
            <TextInput
                label={"App Code"}
                placeholder={"App Code"}
                keyboardType="phone-pad"
                maxLength={6}
                onChangeText={text => {
                    this.setState({ appCode: text.replace(/\D/g, "") });
                }}
                value={this.state.appCode}
            />
        </View>
    );
}

I can see on the console that the appCode value is being updated correctly but the value on the IOS screen doesn't follow the variable. If I enter

1*#+

that is displayed on the IOS screen (the console shows this.state.appCode is 1 for each keypress) but then pressing, for example, 7 and the value displayed on the screen is updated to

17

All the documentation shows this is the correct way to filter the input, and on Android it works but not on IOS