Previous attempt feedback not working

Hi all,

So I'm having this weird problem, a student  has submitted two attempts at an assignment, but I need to edit the feedback that was given for the first attempt.

So following standard procedure I just went into the submission, went down to the previous attempts and then clicked the feedback button on the attempt I wanted to edit the feedback for.

Then I get to a screen that clearly states I'm editing the 1st attempt feedback:

but when I edit the feedback, save it, and then go back into the submission, the feedback from the 1st attempt has not changed!

Can anyone help with this?

I'm using Moodle 2.8

Thanks in advance