Checkbox option variant without icon?

hi I have small problem,

In admin demo store of cscart website in detail product is possible to allow icon or thumbnail

to each variant option for radio buton or select list but not work for checkbox , I upload my thumbnail but can’t save , same problem in global option.

in 1.3.5 is possible to add bulk checkbox option , in 2.1 is only one by one ?

thanks for all