www.makemkv.com

Sorry new to this and not sure if this is normal. So I backed up a bluray movie for the first time into an external hard drive. On the Plex app for Mac OS, the external hard drive is assigned as my library. The Plex app was able to pickup the MKV movies I made in that external HD but for some reason it's not picking up the backed up movie. Is there something I need to do on the Plex app settings? Please advise. Any help or suggestions will be greatly appreciated. Thank you.

I'm not sure what you mean by 'backed up movie', but Plex will pay a .mkv provided that you're hardware / network are powerful enough to stream it.

The intent is whether or not you can pull up a movie in Plex that was ripped to a BD file structure, i.e., MakeMKV's Backup function.