Followed naming conventions yet Plex Media Server for Mac still not adding media to library

1. Followed naming conventions for the following media:
   a. Folder at network share: ~/TV Series/World At War/ {note: Title "World at War" exists in thetvdb.com}
   b. Files: World At War S01E01.mkv,...,World At War S01E26.mkv
2. Ran library update
3. Failed - not added to library
4. Checked logs. It has these entries:
   Feb 23, 2016 08:35:05 [0x7fff72eaf000] DEBUG - Adding subdirectory for scanner: /Volumes/Public/Shared Videos/TV Series/World At War
   Feb 23, 2016 08:35:06 [0x7fff72eaf000] DEBUG - * Scanning directory /Volumes/Public/Shared Videos/TV Series/World At War (parent: yes)
   Feb 23, 2016 08:35:06 [0x7fff72eaf000] DEBUG - Skipping over directory 'World At War', as nothing has changed; removing 0 media items from map.
5. Renamed folder and files from "World at War" to "The World at War", which also exists in thetvdb.com.
6. Ran library update again.
7. Failed - not added to library.
8. Checked logs. Exactly same entries except for title.

Why?

How do I fix this?

My system:
Mac OSX ver 10.11.3