Remote Buddy determines the version of Plex ("old Plex" or "Plex HT") you use during launch and will stick with the result for as long as it runs for performance reasons.

So, if you up- or downgrade your Plex version, please restart Remote Buddy afterwards to give it an opportunity to detect the change and react accordingly.

You may also want to check your system for left over versions of "Plex Helper“ on your system from the respective previously installed versions as these are usually incompatible with the respective other version of Plex and - depending on your setup - will render the remote unfunctional until you clean up after the respectively previously installed version.

Hope that helps.

Best regards, 
Felix Schwarz