In 2014, the Governing Body published a book titled God's Kingdom Rules, and in that book they openly admit the decades-long error of the teaching of the 1874 invisible return of Christ. This book is currently available on JW.org. Here's the key passage:
"5 As we saw in Chapter 2 of this book, the Bible Students spent decades pointing out that the year 1914 would be significant in fulfilling Bible prophecy. However, at that time they believed that Christ’s presence had begun in 1874, that he had begun to rule in heaven in 1878, and that the Kingdom would not be fully set up until October 1914. The harvest would extend from 1874 to 1914 and would culminate in the gathering of the anointed to heaven. Do mistaken ideas such as these cast doubt on whether Jesus was guiding those faithful ones by means of holy spirit?
6 Not at all! Think again of our opening illustration. Would the premature ideas and eager questions of the tourists cast doubt on the reliability of their guide? Hardly! Similarly, although God’s people sometimes try to work out details of Jehovah’s purpose before it is time for the holy spirit to guide them to such truths, it is clear that Jesus is leading them. Thus, faithful ones prove willing to be corrected and humbly adjust their views.—Jas. 4:6."
So, if in a 2014 book the Governing Body openly admitted the error of the 1874 date, why would they be trying to hide information about that error in the February 2017 Watchtower (study edition)?
Well, of course it is possible that the Governing Body came to regret the admission in 2014 of that embarrassing error, and so now has a policy of hiding that error. Or perhaps there are opposing factions within the Governing Body, some members wanting to admit past errors, some wanting to hide past errors, with one faction sometimes getting the upper hand for a time, and then losing power to the other faction.
That's possible. What do you think?