AbstractBaseEntity - the solution to the problem was to wrap the constructor `$this->entityData = $data` in an `if(empty($data))` block.

AbstractBaseEntity.php

<?php

namespace Entities;

abstract class AbstractBaseEntity
{
    protected $entityData = [];

    final public function __construct($data = [])
    {
        if (is_object($data))
        {
            $data = get_object_vars($data);
        }
        
        $this->entityData = $data;
    }

    public function __get($name)
    {
        $method = $this->getMethodName($name);

        if (method_exists($this, $method))
        {
            return $this->$method();
        }

        if (array_key_exists($name, $this->entityData))
        {
            return $this->entityData[$name];
        }

        return null;
    }

    public function __set($name, $value)
    {
        $this->entityData[$name] = $value;
    }

    /**
     * Transforms a property name into a method
     * name. Swaps snake_case to camelCase
     *
     * @param $name
     */
    private function getMethodName($name)
    {
        return 'get' . str_replace(' ', '', ucwords(str_replace('_', ' ', $name)));
    }
}