React-native Picker broken on IOS

I am using expo with react-native to implement a picker. When I launch it on Android the picker works perfectly but when I launch it on IOS, I get the following view. Broken picker on IOS. I am not getting any error messages and I do not want to use any other libraries.

<Picker       style={{
              width: "100%",
              height: 50
            }}
            selectedValue={this.state["country"]}
            mode="dropdown"
            onValueChange={(itemValue, itemIndex) => {
              console.log(itemIndex);
              this.setState({ country: itemValue });
            }}
          >
            {this.state["country_array"].map((item, key) => (
              <Picker.Item label={item[1]} value={item[0]} key={key} />
            ))}
          </Picker>