I stand corrected:
Its not a contradiction. The GT, which is an indeterminate length of time (some assert that Revelation suggests 3.5 to 7 years) precedes Armageddon. Armageddon is the 'climax' of the GT. So all the WT is saying is that some of the anointed will still be 'alive on the earth' during the GT, but it is not known whether they will still be alive when Armageddon starts.
Revelation--It's Grand Climax at Hand! chap. 38 p. 277 Praise Jah for His Judgments!
17 At this point in Jehovah’s timetable, when the sealing of the 144,000 has reached completion, the angels release the four winds of the great tribulation. (Revelation 7:1-3) First, judgment is executed on harlotlike Babylon the Great. The victorious Christ next moves on quickly to Armageddon to destroy the rest of Satan’s organization on earth and, finally, to abyss Satan and his demons. (Revelation 19:11–20:3) No doubt, anointed ones who survive on earth will soon enter into their heavenly reward to join their fellow members of the bride class. Then, amid a setting of universal peace, the marriage of the Lamb can take place!
Sorry for the false alarm