The Marking guide grading form for assignments loses the Feedback comments content if the submission fails due to invalid grade value, and the page is redisplayed to the user with the error message. The Feedback comments section is wiped clean of any content.

During testing for MDLQA-14421, with different invalid marking guide grade values, the grading form would be redisplayed with the relevant error message to tell the user which value to edit. What I noticed was that while the various Marking guide criterion remarks' text content would be returned intact each time, this did not happen with the final "Feedback comments" section, and it would return as empty even if previously containing text.

This would be a nasty surprise for a teacher, if they had put a lot of effort into a final feedback section, and then have it gone, because one of the criterion grade values was invalid. Also, I feel this should be added to the testing steps for Detailed grading with the marking guide MDLQA-14421, as I believe it's relevant to this test.