Google gives 24 images in results for me. If it was only 6 images couple of days ago and now it is 24, that proves @demeldoo 's point.
I had the same problem. We could not advertise on Google PLA for weeks because our images were not getting indexed. robots.txt was blocking thumbnails/ folder by default from CS-Cart. I checked your robots.txt and you don't have that problem. Are you trying to advertise on Google Shopping? You have a huge Sitemap and it froze my Chrome tab but I pulled one of the images out of your website and headers look just fine.
One thing I would recommend to increase crawl rate from Google Webmaster Tools.
And how i increase crawl rate from google webmaster?
The 6 image is what google master tools said that is index.
I have one sitemp make whit screaming frog, and is make whit link and image.
The sitemap is not the problem. I guess that cscart is block my image but is not from robots.txt.
All links in all available languages are located in one file, unfortunately built-in module does not allow to do it. i think.
What do you mean that "All links in all available languages are located in one file"?