cannot view or clean cookies from some web sites
tl;dr tor browser 7.5.6 : cookies not shown in security section in page info even even though the are exists, and can be found in dev tools and cannot delete them.
Using tor 7.5.6 on windows desktop (firefox version:52.9.0) under : page info > security > view cookies . the cookie list of the website is empty.
But in the console inside development tools typing
document.cookie returns a non empty string, say there are cookies in the site, in addition viewing in the network section in development tools it is seen clearly there are cookies in use (the cookies header is not empty). In addition cannot delete the cookies even
document.cookie = "".
how to fix that browses security problem?