Angular - Can't set new HTTP Header

I'm trying to add an Authorization token to my request, but the header never get sent to the API,

    public getIndicators(params: Object): Observable<any> {
        const data = {params : params};
        let headers = new HttpHeaders();
        headers = headers.set('testHeader', 'test').set('test2', 'test3').set('Authorization', ' Bearer token');

        return this.http.post(API_URL + '/dashboard/getIndicators', data, {headers: headers});
    }

The same post request works on Postman if I put the headers in so I thought it could be because the app is served on localhost, so I added

    Header always set Access-Control-Allow-Origin "*"
    Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
    Header always set Access-Control-Allow-Headers "*"

in my apache2 conf and with this simple requests that do not require an Auth header does work

    public login(formUsername: string, formPassword): Observable<any> {
    const data = {
      impersonate: formUsername,
      fmboPassword: formPassword
    };

    return this.httpClient.post<any>(API_URL + '/user/superlogin', data, { observe: 'response' });
  }

Edit: A bit of clarification on the project architecture

I'm running the angular app on my localhost:4200 and got my PHP (CodeIgniter ) api on a docker container (image php:7.2-apache) on port 80, I don't know what could block it.

This is the apache2 conf I set in my Dockerfile

<VirtualHost *:80>

DocumentRoot "/var/www/html/"

ErrorLog "/var/log/apache2/sales-error.log"
CustomLog "/var/log/apache2/sales-access.log" common

<Directory "/var/www/html/">
    AllowOverride All
    Options FollowSymLinks
    Require all granted

    Header always set Access-Control-Allow-Origin "*"
    Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
    Header always set Access-Control-Allow-Headers "*"

</Directory>