[Plugin: FancyBox for WordPress] Fancybox zoom out different in pictures

I have two pictures in one page.
When I click on either of them and press ESC, the plugin zooms in – show the picture – zooms out perfectly.
When I change the picture with the arrows, the plugin does not zoom out when I press ESC. Even if I go back to the first picture. The picture just fades out.
(Both pictures are full visible in the background.)

https://www.ads-software.com/extend/plugins/fancybox-for-wordpress/