Moshiach is Revealed then Hidden

Rabbeinu Bachya, Shemos 4:9

In our future redemption, with the revelation of the final redeemer...the redeemer will be revealed, and he will again be concealed...

So we find with the redemption from Egypt: that Moshe was revealed, and he was again concealed.

And so says the Midrash: 'my beloved is like a deer', just as a deer is seen and then is concealed (hides), so too the future redeemer [Moshiach], will be revealed, and concealed...