Gregory Boyd explains that the prophecy of Tyre did not conclude as predicted:
Perhaps most impressively, in Ezekiel 26-28 we find a lengthy prophecy against the city of Tyre. It is said that Nebuchadnezzar, King of Babylon, would utterly defeat Tyre, killing its inhabitants, plundering all its wealth and leveling all its walls so that it ends up being flat as a rock. Indeed, it is prophesied that it would virtually vanish from the earth and never be found again. Well, it didn’t quite happen that way, as Goldingay notes.
Nebuchadnezzar did lay siege to Tyre, but, while he did gain some control of the city, it was “nowhere near as decisive as Ezekiel had implied” (Old Testament Theology, Vol. II, 83). The city wasn’t completely conquered and laid flat until Alexander did this several hundred years later.
Because his campaign failed, Nebuchadnezzar failed to get much of Tyre’s wealth. So, says Goldingay, Yahweh made “ a new decision.” He decided to turn Egypt over to him in order to repay him for his expenses in his “vain effort” to take Tyre (Ezek. 29:17-20; Goldingay, ibid., 84). The amazing thing is that this campaign also seems to have failed! Nebuchadnezzar invaded Egypt, but “the achievement did not amount to conquest” (op.cit.).