Attribute filters problem

Hello, the plugin looks promising but it keeps failing all of the time I use it with different ways every time. I use the free plugin and when i check the first 2 attribute from attribute filters of category “Χρώματα” of the link I refered, it works correctly (it keeps my selection and filters) but when I check the third attribute and so on it works strangely (it does not keep my selection although it filters correctly). As result I can still check the same filter again and again.
I am thinking of buying the plugin but every time I face a problem such like this one.

Thank you for supporting if the plugin works it will be really good!

The page I need help with: [log in to see the link]