Some Gallery Images dissapear after deleting other images

Version 2.0.40
Wordpress 3.7.1

My problem has happened twice now on 2 different sites, 2 different themes with same plugins . My issue is this:

Set up gallery and all is working fine, I add a new image and gallery is fine, if I delete an image in the gallery then random images disappear. I first thought it was related to thumbnails only and recreated the thumbnails and an error came up however it disappeared before I could copy the error.

Unfortunately, the issue is not just thumbnail related as the whole image just disappears – leaving only the title and description ?

I have uploaded the images again however this does re activate the missing images but creates duplicates as well. When I delete the duplicates the random images disappear again.
The only solution is to completely recreate a new gallery which is quite painful when a lot of adjustments have been made to a gallery.

Has anyone else experienced a similar problem and if so have any advise? I have never experienced this with Next Gen before ??

Thank you in advance and look forward to any feedback.

Kind Regards
Zelldun

https://www.ads-software.com/plugins/nextgen-gallery/