react native: Rendering an array of strings and numbers doesn't work

In the react native app I'm retrieving some data from my backend and then want to display it to the app user: when I log the data I can see that I receive it and stored it properly in the state as an object:

// console.log("received the data: ", this.state.data) ->
received the data:  Object {      
  "a": 48,
  "b": "2021-03-29T17:11:51Z",
  "c": "",
  "d": false
}

But when I try to render that in my view, the screen simply stays empty (no error message):

render() {
  // let me check, if the data is really there
    Object.entries(this.state.data).map(([key, value]) => {
                console.log("key: ", key, "- value: ", value)
            })
  // output:
  // key: a - value: 48,
  // key: b - value: 2021-03-29T17:11:51Z,
  // key: c - value: ,
  // key:d - value: false

    return (
            <View>
                {Object.entries(this.state.data).map(([key, value]) => {
                    return <View key={key}><Text>{value}</Text></View>
                })}
            </View>

    )
}

I also tried this, but still I receive an empty screen:

render() {
    return (
         { this.state.data.map((items, index) => {
              return (
                  <ul key={index}>
                       {Object.keys(items).map((key) => {
                          return (
                             <li key={key + index}>{key}:{items[key]}</li>
                          )
                       })}
                  </ul>
              )
         })}
   )
}

Edit: The full component:

import React from 'react'
import { View, Text } from 'react-native'
import axios from 'axios';

class SuccessScreen extends React.Component {
    baseURL = "https://my-backend-server-URL.com/data"

    state = {
        data: {},
    }

    componentDidMount() {
        this.startGetData();
    }

startGetData = () => {
        
        axios.get(this.baseUrl)
            .then(response => {
                console.log("got the data: ", response.data)
                this.state.data = response.data;
            })
            .catch(function (err) {
                //handle error
                console.log("error getting data: ", err.message)
                return {
                    type: "REGISTER_USER_FAILED",
                    payload: null
                }
            });
    };

    render() {
        console.log("This log will show up")
        return (
            <View>
                {this.state.vehicleData && Object.entries(this.state.vehicleData).map(([key, value]) => {
                    console.log("this log never shows up... key: ", key)   // these logs don't not show up
                    return <View key={key}><Text>{value}</Text></View>
                })}
            </View>

        )
    }
}

export default SuccessScreen;