Thumbs stopped showing

I have photo heavy website, actually it’s purely based on photos..
i have around 10 image galleries at the moment made on nextgen gallery
but now i tried to make yet another and everything went as it has before
but the post is not showing thumbnails only a one picture with arrows on both side to move to next or previous photo within that gallery but no thumbs.

any help would be appreciated

my nextgen is version 2.1.0

https://wordpress.org/plugins/nextgen-gallery/