We need more information than just "sometimes", like in what cases these functions do not work (there will be cases, nothing happens without reason). Without such information we really can't do much.
Also in general you should provide more information like ProjectKorra version, Spigot version, Java version, a debug log (command is /b debug I believe, something like that), and any errors related to PK in the console (if you don't know how relevant an error is, just send whatever may be there and we can work from there).