Gallery problems

Hi,
I’m trying to build a masonry gallery and getting a problem (also similar problems with other types of galleries).

When I add a gallery, the images are just pulled in from the first items in the media library (not the ones I’ve chosen). Also it doesn’t load more images. And when I’m trying to go back to the settings and edit gallery, it is showing no items in the gallery…

Gallery settings:
Image number – 24;
Pagination – Load more
Size setting – Flexible masonry
Gap – large
Image overlay – activated
Image Title and Caption – display neither
Image Link – active

Can you help?

I just starting to build this site, recently activated plugin WP smush.it. Tryed to deactivate it, but it didn’t help.

http://pliusai.lt/fotoseimai.lt/galerija/

Thanks!