In reply to Olliebradbury:
I've figured this bug out now. It's occurring when you sort the logbook by date and you've got routes in there that are from packages released before a certain date. There's ten or so areas affected, including West Country Climbs.
The bug was introduced recently when I modified the logbook view to allow multiple ascents of the same route to appear at different points in the list.
I'll get it fixed and release a new build.