Today I have upgraded from version 1.7.2 to the latest git revision (4ca99b4). My cache directory was migrated and everything seemed to work as expected, until the first update where all my already read feeds appeared again as unread.
Though that it was something from the migration and started to mark the feeds as read.
Then closed liferea and opened it again; a new update made all the feeds unread again. Marking the feeds as read and forcing an update make them unread again.
As it is now it's just not possible to use it (since all the feeds will be marked as unread always).