Nope, no news of a fix yet, but here's what the devs told me in response to a bug report:
This is actually a known bug from the NSPasteboard Object in the Application Kit Framework and we implemented the alert window to let the user know what just happened.
Since it its not a LaunchBar issue we are happy about every hint and are also tracking Apple's progress on this bug.
At the moment there is no known workaround or solution for this particular problem.
Please tell us if you found a way to reproduce this issue.