Apr 22, 2025 19:45:04.223 [17088] ERROR - Couldn't get size of file "M:\Films 1\Heretic (2024)\Heretic (2024) 1080p H265 AAC51.mp4": boost::filesystem::file_size: The handle is invalid [system:6]: "M:\Films 1\Heretic (2024)\Heretic (2024) 1080p H265 AAC51.mp4"
The last time I saw errors similar to this from Plex was a situation where there were invalid characters in the file name. This was pretty recently and in that case it was a \
character. It was visible on the NAS (Linux-based where it’s valid) and caused issues on Windows (invalid).
It’s possible there are some invalid (potentially not visible) characters in your file names (or the directories hold these files). It might be worth your time to rename all these files and their enclosing directories (on the NAS side to prevent any Windows shenanigans), then Plex Dance them, and then scan them again.