This could be a bunch of reasons.
Without more details , I’ll start at the easiest ![]()
-
Usually the one (most common)
Synology FAQ - Questions, Answers, and a few How-To's - #37 by ChuckPa
– Don’t skip any steps or the “Apply to this folder, sub-folders and files” checkbox -
Make sure the naming and structure is per Plex rules.
(PMS is very forgiving but there are some non-negotiable requirements)
https://support.plex.tv/articles/?s=naming+media&search=support_articles