NextGen Gallery problem when adding media to a post

Hello,

So I’ve been having a huge problem with NextGen Gallery in my website https://www.nomadephoto.fr (a homemade Genesis theme). I don’t have this problem on my other website https://www.vincentgaliano.com (Photocrati theme).

Here’s what’s happening:
When I want to add a media in a post or add a featured image from a NextGen gallery, if the gallery has more than 10 pictures (which means more than one page), when I go to the next page the pictures that are shown are the same (but not always in the same order). I hope it’s clear. Basically, if I have 14 pictures in a gallery only 10 will be available to put in a post (unless I use html directly).

What I did:
– Send messages to NextGen (Imagely). So far they were not really helpful.
– Disable all plugins (except NextGen obviously) – NOTHING.
– Change the multisite installation to a single one (the main difference with my other website) – NOTHING.
– Reinstall WordPress from scratch (and copying wp-content) – it seems to be OK. It was yesterday, but now that I’m putting pictures back in posts the problem is back too. I did’nt install anything, I just updated posts.

Here is the plugins list (only the ones that I don’t use in https://www.vincentgaliano.com):
– Jetpack;
– Enjoy Plugin for Instagram;
– Genesis Sandbox Featured Content Widget;
-Genesis Simple Hooks;
– Genesis Simple Share;
– Genesis Translations;
-Instagram Slider Widget;
-MailChimp pour WordPress;
-Simple Share Buttons Adder;
-Simple Social Icons;
-SumoMe;
– Ubermenu + sticky extension;
-Yoast SEO;
-WP Greet Box.

The guy at Imagely told me that they test NextGen with Genesis extensively. The website is quite new, so I’ve been testing some similar plugins in case you ask.

If anybody is skillfull enough to understand my problem, he or she would be a great help. I post 3-8 pictures in each post, I also post entire galleries and NExtGen Gallery is helping me keep things in order.

Thank you!