How to delete synced media when Plex forgets it is synced?

At some time in the past, I synced a movie to plex on my phone. I forgot all about it until this week when I was preparing for a trip and started to sync more content.
I see the movie on Plex in my phone (which I have long since deleted from my Plex server) when I look at Local and Synced Content. I am unable to delete the item via Plex, and it does not show up in the Sync Status on my phone.
How can I find and delete the movie files to free up the space on my phone?

what kinda phone is this? and what os version?

Did you try to select “delete synced content” from the “Sync Status” menu?

Have you tried to delete Plex and reinstall the app on your phone?

Some phones allow you to delete “cached” content related to an app and not delete the app itself which might be an option depending on your phone model and os.

This is on a Samsung Galaxy s8+ running the Oreo beta 7 (yeah, I know.)
It is possible that a Beta OS is the cause of Plex having lost track of the synced file especially since early betas had a bug that caused the SD card to get a new ID on each phone restart.
I’m most concerned with whether I can find and remove it now that the Plex app doesn’t seem to be able to (for whatever reason).

I have not wiped app data or deleted and reinstalled the app. That is a fair suggestion.
I will try that in a couple of weeks after my trip is over, but I’ve just synced down a bunch of movies for the trip and don’t have time to re-sync them before I leave, so I don’t want to try that right now. (the “ghost” movie is not causing any immediate problems)

Yeah I’d wait until you are back to jack with it if it isn’t causing any immediate issues. When you get back around we can pick it back up.

Have a nice trip! See you next fall