Hi, I'm looking into this, and by some quick tests I've just run + through my contact at my host software, LanaBoards itself was not victim to a data leak.
The Passwords application that you posted a screenshot from also identifies when you've used a password for another website, so my best guess is that what that notification was trying to tell you is that the email/password combination you have for LanaBoards has been exploited from another site's data leak where you registered with the same data, so they're advising you to change your password here to avoid your LanaBoards account being compromised. (Plus it sort of reads off that way.)
I'll keep you updated, but so far I can't seem to find any evidence that LanaBoards was a victim of a data leak. I've even checked two password applications I use, neither of which has identified LanaBoards itself as a data leak victim x
(also, we do have a HTTPS/SSL script installed & running, but because some of the embedded images and site functions are coded in with HTTP rather than HTTPS, the padlock may not show on a page if it is technically "partially insecure" due to the images and tools using HTTP instead of HTTPS, but rest assured that all sensitive information is securely encrypted with our script)
