反射异常类不存在

I am having trouble with a Laravel application I am developing using Vagrant.

I have created a few custom classes to help me query an external API, but keep receiving a ReflectionException with the message 'Class ExtAPI does not exist'. These classes are under "app\Lib\ExtAPI"

I am using the Service Container to get the class.

Here is the composer.json:

    "autoload": {
    "classmap": [
        "database"
    ],
    "psr-4": {
        "App\\": "app/",
        "App\\Models\\":"app/Models/*",
        "App\\Interfaces\\":"app/Interfaces/*",
        "App\\Repositories\\":"app/Repositories/*",
        "App\\Lib\\":"app/Lib/*"
    }
},

I don't understand what I am doing wrong because this setup was working previously. Since running my setup on a different host, this is not working anymore.

Any help would be much appreciated.