System language is English, I log in with English, too.
Went to se61, general text, changed zlogin_screen_info, saved, activated.
No change visible on login screen.
Reentered se61 - text looks unchanged.
Searched the forum, the suggestion is to delete the text and recreate it. I did this.
The deletion part worked - the logon screen is now empty.
Creating a new text does not work. zlogin_screen_info exists, but is empty. The logon screen is empty. Changing, saving, activating looks successful until reentering, then it is empty.