Editing it didn`t help. But I finally found the bug. There was somekind of UTF-8 / ANSI bug in my functions.php.
I just copy&paste my hole code to a fresh blank-theme and it worked after that. Really strange.
Thanks for the fast answer. I tried it. I found the settings with hide/show all at ACF. But turning it on/off did not helped.
Did you saw the two pictures, that I edited to my post:
picture 1
picture 2
