Expo background fetch initialize but never running

While developping my react native app, I need to do a periodic background fetch to another server.So I import 2 class from expo :

import * as BackgroundFetch from 'expo-background-fetch';import * as TaskManager from 'expo-task-manager';

and initialize my background task :

const fetchFunc = async () => {    try{        console.log("Hi from fetch function !")        return BackgroundFetch.BackgroundFetchResult.NoData;    }    catch(err)    {        return BackgroundFetch.BackgroundFetchResult.Failed;    }}

Register this task :

async function registerBackgroundFetchAsync() {    try{        await BackgroundFetch.registerTaskAsync("func-fetch", {            minimumInterval: 5, // 5 second        })        console.log("background fetch enabled")    }    catch(err){        console.error(err);    }}

and create a function to execute all of them :

async function initBackgroundFetch() {    if(!TaskManager.isTaskDefined("func-fetch")){        TaskManager.defineTask("func-fetch", fetchFunc)    }    await registerBackgroundFetchAsync();}

Now, I try to launch it when my component is mounted (I use class and typescript) :

class MainPage extends Component{    componentDidMount() {        initBackgroundFetch();    }    .    .    .}

But in my console output I just got the "background fetch enabled" from the registration...I think that my initBackgroundFetch is in the wrong place, but can't find where I need to put it.

PS : my expo diagnostics

Expo CLI 5.0.3 environment info:System:  OS: Linux 5.15 Kali GNU/Linux Rolling 2021.4  Shell: 5.8 - /usr/bin/zshBinaries:  Node: 14.16.1 - ~/.nvm/versions/node/v14.16.1/bin/node  npm: 8.1.0 - ~/.nvm/versions/node/v14.16.1/bin/npmnpmPackages:  expo: ^43.0.3 => 43.0.3   react: 17.0.1 => 17.0.1   react-dom: 17.0.1 => 17.0.1   react-native: 0.64.3 => 0.64.3   react-native-web: 0.17.1 => 0.17.1 npmGlobalPackages:  expo-cli: 5.0.3Expo Workflow: managed