When a synced item is deleted from my phone, or when an item fails to sync (happens regularly with larger files) Plex does not release the unused space. Plex even appears to be grabbing way more storage space than it needs.
I recently synced a few TV episodes. At most they should have occupied a few GBs...however, Plex used all of the available space on my device (around 14 GB). This happens frequently, and deleting/unsyncing does not release the space.
The only solution appears to be to delete the Plex app or its data and start afresh. Not ideal.
Searching the forums seems to indicate that this is a bug that has been around for years.
I love Plex, and I'm very happy to have purchased a Plex Pass. However, it's extremely disappointing to see that one of the main features that I purchased a Plex Pass for is broken. :(