IIRC, the first week it was at the top, apparently. Probably because Grand Order hype or something, and it didn't really have any competition besides Detroit and DS Remastered, which were released before.
Besides, Kinoko said long ago that he wanted EXTRA (and related things) to happen, and in Grand Order he once again suggests that he likes that. I wouldn't really expect him to forget EXTRA/EXTELLA for the time being, TBH.
This is the new era of lunar computers vs aliens.