[Plugin: NextGEN Gallery] Edit Thumb Functionality

I have a question about the Edit Thumb Functionality in Nextgen.

It doesn’t work for me, i only get a smal thumb on the right side and an error icon on the left side. (where you have to select the area for how your thumb would look like.

This is an example for how it should be.

Now, i searched many forums to find an answer. But no solution and every topic went death and closed.

I found the website of the maker of that functionality (before it was embedded in NGG itself) but the download link of those files are death so i could not look if that would work.

Its not my browser (chrome, IE and FF)

Is there any solution for this or should i give up?
If i should give up, is there another way to make those thumbs?
For example, the “NextGEN Image Cropping” plugin does the same thing only just for the real image and not the thumb.

Hope someone can and will help ??

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