When Assignment Enhancements is enabled in a course, it results in SpeedGrader only displaying comments made on the most recent assignment submission. This is a really unfortunate trade-off since the student experience is greatly improved by Assignment Enhancements, but the grading experience when an instructor allows a student to resubmit is significantly degraded by the need to switch back and forth between assignment submissions in order to see the full comment history.
I can speculate on why the experience in SpeedGrader is changed as a result of a change to the student facing UI for assignments/grades, but regardless of the reason that this happens it's a completely unanticipated change for anyone who has access to SpeedGrader. I suspect that faculty who have contacted with concerns about this change to viewing assignment comments will simply turn assignment enhancements off lessening the quality of user experience for their students since having it turned on creates a significant inefficiency in their own user experience when grading.
This is unfortunately very similar to the issue that came up with the roll-out of checkpoints in the discussions redesign where an improvement that is primarily about the student experience is implemented in a way that is problematic for the teacher experience. A work around has been implemented in that case which remedies the issue, but in any such instance it's vital to consider the roles of all users when making changes to the platform such that improvements for some roles are not implemented in such a way that it reduces the quality of the UX for other roles.
