To answer your question the title is probably no longer tracked. The game pages should clarify this. They should state that a title is no longer being actively tracked. I suspect that the vast majority of current generation titles are no longer tracked. The logic being that it is more expedient to track the three hundred top selling titles then to track all three thousand titles available. Actually it would almost be unimaginable that such a degree of tracking would take place. Let alone how inaccurate a small sampling would be in regards to any title that sells less then a thousand units every week globally.
Answering your question it would take only three hundred units a week for this title to sell ten thousand more units in eight months. So I would suspect that the title has crossed half a million. In North America alone even if you let that market count for half the sales its hard to image three copies of the game not selling every week in every state. Were sales less then that you wouldn't be finding the title on any major retailers shelf, and its right there to be seen. I know I have seen it. However there are a great many titles released much more recently that are nowhere to be seen.
There is hope however developers do make it a point to release sales figures for their products. So perhaps Mistwalker or Microsoft will share their sales figures for the title at some point, and the tracker could be amended.
Let me say this is just educated speculation. I have no idea how Ioi quantifies his data. However its far more logical that he doesn't track the shallow end of sales. Rather then a title just stopped selling altogether.







