Headers are not being sent in iOS but working in android for Axios React Native

I'm using Axios for sending http requests, it's working fine for Android, but the headers are not sent in iOS, here is my code:

Axios.get('/patient/doctor/search?page_size=10&page=1')
        .then(function (response) {
          // handle response
        })
        .catch(function (error) {
            // here it goes with 401 error code
        });

and in my interceptor:

Axios.interceptors.request.use(async config => {
try {
    const user = await AsyncStorage.getItem('user');
    const userData = JSON.parse(user);
    if (userData.token) {
        config.headers = {
            ContentType: 'application/json',
            Authorization: 'Bearer [JWT-TOKEN]'
        }
    } else {
        config.headers = {
            ContentType: 'application/json'
        };
    }
} catch (e) {
    config.headers = { 'ContentType': 'application/json; charset=utf' };
}
return config;
}, error => {
    return Promise.reject(error);
});

Any Idea ?