I found the answer to the label half of the question.
If you click on the Label box in the Marks card it will pull up an option box that will allow you to make the following change.
"Label" in the "Marks" section and uncheck "Allow labels to overlap other marks" checkbox.
It still does not resolve the issue of not seeing the E3 because it is on the same point as the E2 mark.
Jennifer is on point! The 2 marks are on the exact same coordinates, which makes them overlap one on top of the other. This creates the effect you describe when you hover over them with your mouse, you're really only selecting the mark on top.
You could adjust the coordinates slightly with a couple of calculated fields. If you do that, the marks are not in their original position, but you can see them separetly. It just depens on what's more important: seeing the marks on the exact position, or seeing that there's 2 of them. See attached, there are comments on the calculated fields.
Label_Doubt_v1.twbx 18.3 KB