Votes not registered

Hello,

Some votes are not registered properly – I had someone who has never rated before try rate from a different location and it says he has already rated that post. This issue is only with some posts: http://tmff.net/movies/tar-barrel-in-the-dale/ while voting other works.

I have no caching plugins enabled (had wp fastest cache – which they say it’s compatible with your plugin but I have deactivated it thinking that caused the issue but it still does not work). It’s quite weird, this happened before also because of a caching plugin but now it should work since I deactivated it.

The logging method is by cookie and IP.

Thanks

https://ww.wp.xz.cn/plugins/wp-postratings/