okay i think i found the bug.
I have now selected “Single-line text” as the field type for the import.
<?php if( get_field('image') ): ?>
<img src="<?php the_field('image'); ?>" />
<?php endif; ?>
So the picture is now also shown to me.
I think I will now add an “if query” to ask whether an image is “uploaded” as text, or in the traditional way using the field type “image”.
Or are there suggestions for improvement?