If Plex had already matched your files to a certain show/episode, it’ll remember that even if you rename the file. This can actually be quite helpful to avoid your files getting re-matched every time you do some minor adjustments.
In such an example you need to make Plex forget it knows the file. This can be done by using the procedure known as Plex Dance – you kind of did some of the crucial steps when you moved the “Angel Link” folder outside the library folder and re-scanned the library before returning it.
