Please find the original item, for which you typed in this summary.
Determine its guid="... (find it in the Plex XML info )
Now find the guid of the other item, which has the copy of the description. Do they differ?
btw. you can write a description into the metadata of an mp4 file. Using mp3tag, you open the extended tag editor and add PODCASTDESC
There are a few other things you can embed.
See What MP4 tags can be read into Plex with local assets agent? - #11 by OttoKerner
I recommend you to embed as much metadata as possible, instead of typing in the metadata into Plex. That way they can survive a crash or re-creation of the server.
