signalR Azure : url request to start the negociation is empty

Hello,
I used signalr to communicate the server to client application.
I have an issue when I deployed on the server.

The request used for the negotiation is empty (see print screen and in the code is connect.start()). But the url is not empty when I put the debug information. You can see in the picture baseurl contain the value in the configuration string. :

The code to start the connexion.

const options: IHttpConnectionOptions = {  
    accessTokenFactory: async () => {  
  
      const request = {...loginRequest,  
        account: accounts[0]};  
      var token = await instance.acquireTokenSilent(request);  
      return token.accessToken;  
    },  
    transport: HttpTransportType.WebSockets   
  };  
  
 const connect = new HubConnectionBuilder()  
        .withUrl(process.env.NEXT_PUBLIC_SIGNALR_URL!,options)  
        .configureLogging(LogLevel.Debug)  
        .withAutomaticReconnect()  
        .build();  
  
    console.log("signalR connection")     
  
console.log("baseUrl:", connection.baseUrl)  
      if(!connect .baseUrl)  
        return;  
  
      connect   
        .start()  
        .then(() => {  
          connection.on("target", (message) => {  
            let obj: T = JSON.parse(message);  
              
            setMessage(obj);  
          });  
        })  
        .catch((error) => console.log("signalR:", error));  

The client application is done in react. So When I launch the application locally, the negotiate step can be done with the correct url.

I configure the CORS to open the url. The configuration in Azure contains the url because I put the url in the console log.