Hello Francesca,
Thanks for highlighting this problem with the Open Badges backpack connection. It is reported in the Moodle Tracker as MDL-57429, though unfortunately there is no solution as yet.
To indicate that you would like the issue to be fixed as soon as possible, please vote for it (you'll need to create a tracker account, as mentioned in the tracker introduction guide). You may also wish to watch the issue so that you receive email notifications of updates.