My filter seems to be set to 'all regions' at the moment... next time it pops up I'll have a look though. It definitely seems to be a cookie issue from TM's end. I figured out logging out & back in (or clearing the cookie) seems to correct it temporarily but it just happens again an hour afterwards. Just strange that it always happened on Firefox but never used to happen on Opera until recently. I wonder if they changed cookie handling in an update and unknowingly triggered the bug.
Nobody tests ANYTHING for compatibility with Opera+Linux. Life of a contrarian.