Wrong page displayed when adding two consecutive annotation replies

STEPS TO REPRODUCE:

1. Login with Admin or with an user
2. Go to a page, select some text (or a word)
3. Press CTRL + M and fill in some annotation text
4. Click "Add annotation" button
5. Click on the small yellow icon correspondent to the annotated text
6. Click 'Reply' Button
7. Write a reply
8. Click 'Add Comment'
9. Click again "Reply" Button from annotation box

EXPECTED RESULTS

The user is directed to the 'Comments' tab where another reply can be added.

ACTUAL RESULTS

In IE (v.11), Edge (v. 16) and Chrome (v.63), after clicking again the 'Reply' button from the annotation box, a plain page of the comments is displayed (screenshot attached). In Firefox (v.57), after clicking again the 'Reply' button, nothing happens.