Composer autoload in own package / class not found - composer-php

Question

I've tried now some different approaches and read articles here and elsewhere but i can't figure out what i'm doing wrong.
I'm developing a package and I want it to be installed via symlink in a different project to develop both parts simultaneously without the need of updating the dependencies over and over again.
The thing I cant get to work is the autoloading.
Here is my setup:
Project composer.json
{
"repositories": [
{
"type": "path",
"url": "../../FormTableComponent",
"options": {
"symlink": true
}
}
],
"require": {
[...]
"bluechord/formtablecomponent": "#dev"
}
}
FormtableComponent Folder Structure
FormTableComponent/
src/
| Container.php
composer.json
FormtableComponent composer.json
{
"name": "bluechord/formtablecomponent",
"description": "...",
"autoload": {
"psr-4": {
"BlueChord\\FormTableComponent\\": "src/"
}
},
"require" : {
[...]
}
}
FormtableComponent Container.php
<?php
/**
* FormTable Container. The Container Class that registers all Parts of the
* Component.
*/
namespace BlueChord\FormTableComponent;
class Container {
function __construct() {
}
}
When I try to use the class and instantiate it I get
Uncaught Error: Class 'BlueChord\FormTableComponent\Container' not found
Thanks for your help!
ADDITIONAL INFO:
A simple Test.php which reproduces the error inside the project
<?php
require_once 'bin/vendor/autoload.php';
echo "BCOSP Test";
use DebugBar\StandardDebugBar;
use BlueChord\FormTableComponent\Container;
$debugbar = new StandardDebugBar(); --> WORKS
echo StandardDebugBar::class ."\n";
$container = new Container(); --> ERROR
echo Container::class . "\n";
Composer
The vendor/composer/autoload_psr4.php does NOT contain any array key for my package.
If I run composer dump-autoload inside my main project nothing changes.
If I run composer dump-autoload inside my package it creates the correct autoload_psr4.php