To reproduce in 3.1.1:
- Save a comment to your quicklist if you don't have any yet
- Create a new comment (i.e. draw a new comment box)
- Select a saved quicklist comment to populate it
The quicklist comment appears very briefly but then the entire comment box disappears. Note it is possible to update existing comments by selecting a quicklist item, but not to add them as new comments.
Tested in Chrome and Firefox on Ubuntu and Windows 7 so far.