Checking or unchecking a task changes the status of all tasks

We have created an issue in the issue tracker of our project with a bunch of tasks on which multiple developers are working (quick fixes). When the fix is done, he marks the checkbox to indicate that this task is done.

Now, when dev 1 marks task 1 as done, the status isn't updated on the screen of dev 2 (what is unfortunatly, but that's another issue). When dev 2 marks task 2 as done, it also marks task 1 as not done at the same time.

It seems that the onclick of the checkbox sends the status of all checkboxes, but it should only send the status of the clicked checkbox.