When a file is manually replaced, for example after converting from an mp4 to an mkv; radarr decides to delete everything in that movies folder: posters, backdrops, subtitles, NFO files, leaving only the new video file; even though none of these were created or managed by Radarr ever.
This causes Emby to have to rescan/reidentify the item, re-downloading all the extra data, and it’s now lost all custom metadata that was stored in the nfo, particularly the original date added to emby and it now has no subtitles.
How can I prevent this?
Before you spend too much time on that, you can create an issue on the Github page. Seems fairly active. Might get a better response there.