After researching this further online, I believe that at the time, the top seller data came from the Softsel Hot List, which was the closest thing there was to a top seller list for computer software in those days.
The data for those lists came from sales by Softsel themselves. So if software wasn’t sold at all through Softsel then it wouldn’t show in these lists. It was a rather big distribution channel though, which I believe you (Ken) contributed to setting up in its infancy.
Do you think it is possible that you stopped distributing the King’s Quest games through Softsel mid 1985?
If so, that would explain their sudden departure.
Best regards,
Lance