New images won't show in the gallery

Hello,
I installed your great plugin, it’s working fine except the situation when I have an old gallery, and after I put there a new photo, it’s showing it as a thumbnail, but not as a photo. So when I click the thumbnail of a new photo, it is not appearing as a large version.

Here is a screenshot.
As you can see, third thumbnail selected, but it is not shown.

Plugin version: 1.2.3.2

https://www.ads-software.com/extend/plugins/slideshow-gallery/