I checked the tracker, https://tracker.moodle.org/browse/MDL-42245 etc can't find a bug, and as below, no move arrows or DnD to change sort order of courses in a category:
Hi Derek,
Sorry I can't think of a reason why you shouldn't see drag and drop icons and move arrows, but just wanted to confirm that they should be there! I notice you're also missing the 'Sort courses' link. Have you tried using a different theme?
Hi Derek,
I think you and Helen are looking at two different pages. At the top right of the page in your picture, click on Course Categories and Courses. Select Courses from the drop down list and you will then probably have to pick which category, but then you should see a page like in Helen's picture.
HTH,
AL
I also had this problem this morning on Moodle 3.0.3+. I looked at the source code and the sort features are hidden if the number of courses in the category, does not match the number of courses the user can see in the category.
I figured somehow the course count was out of sync. So i added a course and all the sort features came back . I then removed the course and I still had all the sort features.
I have no idea how to reproduce this or how it happened or of its a problem in later Moodle versions. So I have not filed a tracker issue. I hope this helps someone though.