So, unmapped means not linked to Sonarr, clearly I’ve misunderstood the process of mapping my library to Sonarr. The library is properly organised and was working happily with Sonarr but I had to rebuild my NAS and thus needed to reinstall Sonarr. I have attached part of one of the log files - not sure of the best way to provide more.
2022-04-25 22:46:30.5|Error|VideoFileInfoReader|mediainfo is required but was not found
[v3.0.7.1477] System.DllNotFoundException: libmediainfo.so.0 assembly: type: member:(null)
at (wrapper managed-to-native) NzbDrone.Core.MediaFiles.MediaInfo.MediaInfo.MediaInfo_New()
at NzbDrone.Core.MediaFiles.MediaInfo.MediaInfo…ctor () [0x00006] in M:\BuildAgent\work\63739567f01dbcc2\src\NzbDrone.Core\MediaFiles\MediaInfo\MediaInfoLib.cs:71
at NzbDrone.Core.MediaFiles.MediaInfo.VideoFileInfoReader.GetMediaInfo (System.String filename) [0x00021] in M:\BuildAgent\work\63739567f01dbcc2\src\NzbDrone.Core\MediaFiles\MediaInfo\VideoFileInfoReader.cs:44
2022-04-25 22:46:30.5|Info|ExistingMetadataImporter|Found 0 existing metadata files
2022-04-25 22:46:30.5|Info|ExistingSubtitleImporter|Found 0 existing subtitle files
2022-04-25 22:46:30.5|Info|ExistingOtherExtraImporter|Found 0 existing other extra files
2022-04-25 22:46:30.5|Info|ExistingExtraFileService|Found 0 extra files
2022-04-25 22:46:30.5|Info|RefreshSeriesService|Updating The Untold History of the United States
2022-04-25 22:46:31.0|Info|RefreshEpisodeService|Starting episode info refresh for: [263532][The Untold History of the United States]
2022-04-25 22:46:31.0|Info|RefreshEpisodeService|Finished episode refresh for series: [263532][The Untold History of the United States].
2022-04-25 22:46:31.0|Info|DiskScanService|Scanning The Untold History of the United States
2022-04-25 22:46:31.1|Info|DiskScanService|Completed scanning disk for The Untold History of the United States
2022-04-25 22:46:31.1|Error|VideoFileInfoReader|mediainfo is required but was not found
[v3.0.7.1477] System.DllNotFoundException: libmediainfo.so.0 assembly: type: member:(null)
at (wrapper managed-to-native) NzbDrone.Core.MediaFiles.MediaInfo.MediaInfo.MediaInfo_New()
at NzbDrone.Core.MediaFiles.MediaInfo.MediaInfo…ctor () [0x00006] in M:\BuildAgent\work\63739567f01dbcc2\src\NzbDrone.Core\MediaFiles\MediaInfo\MediaInfoLib.cs:71
at NzbDrone.Core.MediaFiles.MediaInfo.VideoFileInfoReader.GetMediaInfo (System.String filename) [0x00021] in M:\BuildAgent\work\63739567f01dbcc2\src\NzbDrone.Core\MediaFiles\MediaInfo\VideoFileInfoReader.cs:44