Migration Assistant from Time Machine (after HighSierra update) : user folder is there but does not appear in the login page

Migration Assistant from Time Machine (after HighSierra update) : user folder is there but does not appear in the login page. After the update trouble, I had to create a new user, then use migration assistant to get my Time Machine backup -and download my original user folder. Now when I login, I only have the choice of the User I created to get out of my stuck update, even though my original user folder is there, in the Users folder.

So, in my Users folders, there is :

- the folder of the user Mr X, which I created to be able to get out of the update that went wrong,

- the folder of the user Mr Z, my usual pre-update-that-went-wrong folder, where all my stuff is (I see it, it is all there).

When I login, only Mr X appears, I can't choose Mr Z.

Any suggestions ?