Comment bubbles above comment boxes no longer have an option to pin/unpin comment bubbles. This functionality allowed users to choose whether or not to show the comment bubble, which was useful for organization.
1. Open Editor (any project)
2. Open Blueprint (any)
3. Create Comment Box
4. Look at comment bubble above comment box (may need to scroll view out for it to appear).
No pin option is present
Small pin icon appears, allowing user to pin/unpin a comment bubble to the eventgraph so it can be seen/hidden at all times.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-17576 in the post.