You're getting a 404 error because Plex recently changed the URL for their watchlist API. Since that URL is hard-coded directly into Overseer, sync is currently broken on the :latest branch. The :develop branch gets much more frequent updates, and has already been fixed. Switching to that should solve the 404 error.
#Watch list failing
wraith sundial
hallow fable
Hi there, there is a way to fix this, Plex changed the watchlist URl so you have to update it with in docker, Here is how I fixed it.
Open docker, View the files in the container, go to app / dist/ api/ plex.tv , Edit that file
Scroll down near the bottom looking for https://metadata.provider.plex.tv/ , It appears twice
Replace it with https://discover.provider.plex.tv/
Save the file and restart the container,
This should then fix the watchlist issue