Feedback really should not be used in this use case. This is what submission comments in Assignment 2.3+ is for. The submission comments are for commenting on the submission and the feedback is for commenting on the grade.
Based on the discussion so far it seems that they issue is that you are trying to provide the student with comments on their submission and not a comment/feedback on why they are getting the grade that they are getting. And with Assignment 2.3+ there was a change to separate these workflows where as previously they were the same workflow.
If you could explain further in the ticket why you would want to create gradebook feedback without an actual grade that would make for more support. I do not believe this functionality has changed at all in 2.5 it is just that when the ticket was created 2.5 was not released yet.
