Lightbox Navigation not working with wp gallery

Hy

I got the Problem that the lightbox(TosRUs) Navigation arrows and Thumbnails are missing on a wp gallery created with the visual site editor.
when i insert the same Gallery with a shortcode, navigation arrows and thumbnails are loaded.

Any idea why this is happening?

have a look at this site: url in next private post
above the <hr> tag is the working gallery made with shortcode, below the <hr> is the gallery made with the visual wp editor.

Thanks in advance
regards
Najjo