I think I found out how the comments got deleted. Apparently if you hide the comments field, and then “Save all quick grading changes”, it deletes the comments! Although it didn’t if I was showing 20 students, but did if I was showing 50 students.
Gradebook
Comments/feedback disappearing
הדיון ננעל, כך שלא ניתן יותר להגיב אליו.