Attack on Titan Season 3 showing only the first 12 episodes

Plex Media Server Metadata & Adding Files
8

I’d feel better suggesting:

Attack on Titan (2013)/
....Season 03/
.........Attack on Titan (2013) - s03e14 - Thunder Spears [x264 AAC].mkv

Plex ignores everything in a [bracket], but if it works, it works.
TVDB is having issues - could be a local problem for the OP.
Keep trying it now and then, but if you really want a ‘Do-Over’:

Plex Dance the whole show:

All the Steps, in the Order Described, or it WON’T WORK.