j, I've just reproduced this, but it is intermittent.
It seems to happen most often with the first post in a thread, or a thread with only a single post.
In this thread for example:
1st post, Fok's flyout, I get it to pop, and then it goes away when I try to roll down, unless I move my cursor precisely under the little blue triangle. Other posters, I can scroll with focus over most of the flyout.
Very carefully moving the cursor down precisely under the blue triangle often gets me int the flyout.
I also now notice this is happening with your flyout in this thread, while I have this editor open.
Possibly something with avatars with custom functions? The ones I have seen this happen to have custom status, admin, affiliate vendor.
Custom member titles, between the member name, and the member status. I can now consistently reproduce the bug in that case. I think that is the key.
I'd pm you about this, but I can't get your flyout to stay up...
Update: I have reproduced in Safari, so it's not browser dependent. Don't have a Windows or unix box at home to test, it's possible it Mac dependent, but I'd be surprised.
j stands for jerk
I reproduced with vox and others, all with a custom title