If you see JS errors related to the extension or HTTP errors in the console of the developer tools, please file an issue with the errors on GitHub. It would help understanding what's going wrong.
EDIT: it could be related to the fact that SingleFile is maybe more strict regarding the HTTP header "Content-Type". For example, it will discard images with "text/html" as content type value.
EDIT: it could be related to the fact that SingleFile is maybe more strict regarding the HTTP header "Content-Type". For example, it will discard images with "text/html" as content type value.