I was playing second playthrough. Not long after I entered Defiance Bay and Act II, suddenly I realized that my main quest has not been updated since Caed Nua. It was the quest named 'Old Watcher' and it said I should confront the watcher whose name I forgot. Of course, I already met him and killed him so that I could repair the eastern tower so I can get to Defiance Bay.
Actually, main quest proceed with almost no trouble. I met Woedica's ghost follower at the First Fire and he directed me to the sewer. However, journal doesn't get updated and more importantly, I do not get any reward from the main quest. Concerning side quests, their journal updated normally and I get rewards normally, too.
I already tried console command that force-proceed the quest progress with IE mod installed, but it didn't do anything on the main quest while the console command do its job on the side quests. I suppose it is because my main quest 'The Old Watcher' is already completed in my flags.
Maybe I can just play with intuition to complete the second playthrough's main quest and fill the lacking XP from more side quests (another difficulty increase mode for myself, I guess), but the bug is quite unsettling and I want to fix it if there is a known solution.