Page 2 of gallery shows no images

I am running WP 4.8 with : NextGen Gallery version 2.2.10, NextGEN Pro version 2.5.5, Photocrati Pro version 5.0.2

One of my galleries “land, sea & city scapes” which has 26 images (it is set up for 25 images per page) in it is only displaying the first 20 images then offering page 2 option – but page 2 shows no further images. These images are in the gallery and show in the slide show scroll for eCommerce.