Moodle 3.5.5+ (Build: 20190322). Tests were performed in our custom theme based on Clean, and separately in Boost.
We use Rubrics (Advanced grading) for some of our Assignments. Some instructors have recently reported that they were having trouble selecting some rubric items, so I investigated. It seems that the selectable area for some rubric boxes is smaller than it would appear. That is, you cannot click and select a rubric item, even though you have put your cursor in an area that seems to correspond to it.
For example, see the screenshot below. If I hover my mouse in region 1, then the box is highlighted, i.e. the background changes from white to green (which is what the screenshot is showing, even though it did not capture my cursor). However, if I hover my mouse in region 2, then no highlight occurs. However, if I hover my mouse directly over the text that is above region 2, then the highlight occurs as expected.
Observed behavior: rubric box does not highlight (change color) if the mouse cursor is hovered over arbitrary regions of the box. It only highlights if the mouse cursor is hovered directly over the text.
Expected behavior: the rubric box should highlight if the cursor is hovered anywhere in the box.
Possible cause: I think that this happens when the text length is short for all boxes in the row. The boxes have some kind of minimum height because of the feedback boxes on the right, but the text is not long enough to meet that height. The box with region 1 is in a row that contains boxes with longer amounts of text, so I assume that somehow the selectable-box height is applied to the whole row.
Version notes: We recently upgraded from 3.5.3 to 3.5.5, and we only started getting these reports recently. So, that makes me think that something changed in 3.5.4 or 3.5.5, but I cannot say for certain. I also do not have proof that this worked the "Expected" way in 3.5.3 or earlier, but I would think this is something I would notice.