Classic issues to check are:
- permissions → is the local
plexaccount able to see the files in the folder linked to your library? chmodon its own might not be sufficient if you’re e.g. mounting a folder from an external drive with default configurations.- file naming → have you named those tv episodes according to Plex naming schema (incl. the required folder structure)? Plex will ignore videos that don’t have a pattern/segment providing season/episode number information
for #1 and #2 I strongly recommend to check out the Linux tips & tricks: