MySQL Using SUM with multiple joins

I have a projects table and a tasks table. I want a query that gets all projects and the sum of the time_spent columns grouped by project id. So, list all projects and get the total of all the time_spent columns in the tasks table belonging to that project.

With the query below I get the latest added time_spent column and not the sum of all the columns.

SELECT `projects`.`id`, `projects`.`description`, `projects`.`created`,
    `users`.`title`, `users`.`firstname`, `users`.`lastname`,
    `users2`.`title` as assignee_title, `users2`.`firstname` as assignee_firstname,
    `users2`.`lastname` as assignee_lastname,
    (select sum(tasks2.time_spent)
    from tasks tasks2
    where tasks2.id = tasks.id) as project_duration
FROM (`projects`)
LEFT JOIN `users`
ON `users`.`id` = `projects`.`user_id`
LEFT JOIN `users` as users2
ON `users2`.`id` = `projects`.`assignee_id`
LEFT JOIN `tasks` ON `tasks`.`project_id` = `projects`.`id`
GROUP BY `projects`.`id`
ORDER BY `projects`.`created` DESC

projects table:

tasks table:

SELECT p.*,
   (SELECT SUM(t.time_spent)
    FROM tasks as t
    WHERE t.project_id = p.id) as project_fulltime
FROM projects as p 

Maybe your JOINs don't fetch all the data you need, like users.