TLDR: Files were added with a date of 2098. This caused the Plex DB to always have these media files as “Recently Added”. Had to go through and “touch” each of them.
I recently had the same problem. My “Recently Added” would show the same movies/TV. I thought this was a DB problem and went through a ton of steps to fix what was not actually broken.
On a whim, I went a looked at each of the files and noticed they had dates years in the future (I.e 7/21/2098). I had not realized that Plex adds to its database based on the file date rather than the date its added to the database.
So to fix this (Linux system), I SSH’d to the files and did a "touch ". That changed the date to today. I then did a find for all files with a future date, and found quite a few of them. I need to do more digging as to what is causing that.
One other note: once I changed the date, Plex did not update its DB entry. It kept the old 2098 date. I had to remove them from the folder, rescan the folder to have them removed and then re-add them to have them pick up the new date.
Feature request. Can Plex put in a check for any files being added that may have a date well into the future, and then just add today’s date in its place?