After inserting the three celestial altars, it becomes a full moon for a day right? Well when I did it, the full moon happened indefinitely (I assume). When I left the server and hopped back in it fixed itself. This also happened after killing the celestial champion, the day that is a full night happened indefinitely(I once again assume). I waited several days for the days to run out so some time was wasted, nevertheless, I hope it gets fixed!
Insert all three altars
Kill celestial champion