[Issue]: Items in collections disappear after refreshing metadata

[joshuaavalon]

Please describe your bug

I found that no matter if you add item through Web UI or plugins. The items in collections will be removed after refreshing metadata.

Reproduction Steps

1. Start a new Jellyfin 10.9.6
2. Create a movie library with at least two movies that exists the same TMDb Box Sets
3. Install Jellyfin TMDb Box Sets Plugin
4. Run the plugin the add movies to collections
5. Go the the collection and run Refresh Metadata > Replace all metadata
6. All the items in the collection disappear

I can confirm it works before 10.9

Jellyfin Version

10.9.0

if other:

No response

Environment

- OS: Debian  11
- Linux Kernel: N/A
- Virtualization: Docker
- Clients: Web
- Browser: Chrome
- FFmpeg Version: N/A
- Playback Method: Web
- Hardware Acceleration: Yes
- GPU Model: RTX 4060
- Plugins: Jellyfin TMDb Box Sets Plugin
- Reverse Proxy: Traefik
- Base URL: N/A
- Networking: N/A
- Storage: Local

Jellyfin logs

Not related

FFmpeg logs

No response

Please attach any browser or client logs here

No response

Please attach any screenshots here

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[jellyfin-bot]

Hi, it seems like your issue report has the following item(s) that need to be addressed:

• You have not filled in the environment completely.

This is an automated message, currently under testing. Please file an issue here if you encounter any problems.

[Liquoriced]

I wonder if this is connected to #12032 which seems to have been forgotten.

[joshuaavalon]

I though it may be caused by merging data during refresh . So, I create #12156.

However, it may be caused by validation changes in /MediaBrowser.Controller/Entities/Folder.cs after I look around more in the code. I am not familiar with the code flow. Can maintainer take a look at it?

[maximo1984]

I wonder if this is connected to #12032 which seems to have been forgotten.

Yes, sad to see that my report is falling by the way side for such an important thing that needs remedy.

[Shadowghost]

If you're using the boxset plugin this likely needs to be fixed over there. Issue should be that the LinkedChildren are discarded on merge instead of replaced.

[joshuaavalon]

@Shadowghost I believe it does not belongs to the plugin because the plugin is only a metadata provider.
I have checked the API that metadata provider cannot access LinkedChildren. A metadata provider can only provide a metadata result (for user to choose), the merging is handled by Jellyfin

[Shadowghost]

Then we need to either change the specific implementation of MergeData in BoxSetMetadataService or modify the provider handling in MetadataService. I don't use the plugin, so I haven't experienced this myself. My manually created Collections work just fine.
Not sure if I can find the time over the week to install the plugin and debug it.

[joshuaavalon]

@Shadowghost I think manually created collections work fine because the is no default metadata provider. So it won't try to refresh metadata.

I have tried to add manually or via plugin. They work fine until a refresh happen.

[Liquoriced]

I can confirm that this is not caused by the boxset plugin: I didn't have the plugin installed and I edited the collections, but when I re-scanned the media, the default collections returned.