It's quite rare, but sometimes users may see that Plex Media Server retrieves all the normal textual metadata (description, director, cast, rating, etc.) for a library item, but no images are retrieved.
Not Using an Agent that Gathers Metadata
When you create or edit a media library, you can set the metadata agent to use under the Advanced tab of the library window. When creating a Movie or TV Shows library, the default metadata agent is one that will gather metadata from online sources. If you've changed the agent to
Personal Media or
Personal Media Shows, though, then those won't attempt to gather any metadata.
The Metadata Site Doesn't have Images
Obviously, one explanation would be if the metadata resource (such as The Movie Database or TheTVDB) itself doesn't have images for the item in question. In that case, you could try to add the images to the metadata site yourself and then try to refresh your library item in a couple of days when the new images have been cached. You could also manually add your own images in the Plex Web App if you wanted.
Something Local is Blocking Connections
If the images are present on the metadata resource site, then the most common reason you'd see this is if something on either your computer or network is blocking the connection to retrieve the images. In these cases, it's often caused by a firewall, proxy, or router feature.
Beyond a standard firewall or proxy, you may also run anti-virus, anti-malware, ad-blocker, or similar software that can behave in many ways as a firewall or proxy. In the past, we've specifically seen some of the following cause issues for users:
- DD-WRT (or other router) firmware ad-blocking features
- Kaspersky Total Security "Anti-Banner" module
- Little Snitch
- Peer Guardian
There are undoubtedly other applications that could cause issues, too.
Try disabling your firewall, proxy, or other software and see if that makes a difference.
Metadata Cache Servers
For most metadata content, Plex makes use of cached metadata served by custom servers. This is done so that those providers don't get slammed by the mass of Plex users querying for content metadata. If you have something on your computer/network blocking things, you can try whitelisting the following:
File System Doesn't Support Symlinks/Hardlinks
The metadata–and particularly artwork–stored on your Plex Media Server makes use of symbolic links/hard links for referencing the same item from multiple locations.
Some filesystems such as Microsoft's Resilient File System (ReFS) or "drive pooling" implementations don't correctly handle things in such a way that the links used for the metadata work correctly.
If you place your Plex Media Server data directory on such a file system or drive pool, you may run into problems.