In an earlier version of moodle it was possible for a user to correct answers in an feedback.
So after saving the feedback it was possible to restart the feedback and the already entered answers were displayed and you could make changes to the forst attemp.
In the version 3.1.4 (or maybe prior) you can not access a feedback again when you finished it. Every new attemp to enter a feedback leeds in a new entry (if multiple feedbacks are allowed) or a message says that you have already finished the activity.

Please change back to the posibility to correct answers in an feedback.

One more problem with the actual behavior is, that a user can NOT look again on the feedback and con NOT get any information, what answers a user gave because a user can not access the feedback again.