Rumor Boss "Unknown Area" possible glitch

I just had the same problem. Also a lich but in Central Mercia.
I have explored every possible place in case I had just missed a secret room but that wasn't the case.
Some details that might possibly help solve the problem: I got the first rumor in the tavern in the back of Freetown. The unknown location message appeared when I went to gather more information in the other tavern. I also have another rumor boss (skeletal warlord) running, and have the precise location of him already, but since he doesn't give a black shard I wanted to find the lich first.
Hope this helps, I'll send the ek.bak file too later today.

No need to send, in theory this is fixed for next update.

Because this is a "fixed" problem, locking thread. If the issue continues after the next update, a new thread would be better to help find the issue. Fingers crossed the issue is fixed.