Sonarr not recognizing certain season packs

Sonarr version (exact version): 3.0.4.1052
Mono version (if Sonarr is not running on Windows): 6.10.0.104
OS: Ubuntu 18.04
Debug logs:
Failed

21-1-4 12:49:05.2|Debug|Parser|Parsing string '[RH] Katanagatari [BDRip] [Hi10] [1080p]'
21-1-4 12:49:05.2|Debug|Parser|Unable to parse [RH] Katanagatari [BDRip] [Hi10] [1080p]

Succeded

21-1-4 13:11:48.4|Debug|Parser|Parsing string '[RH] Katanagatari S01 [BDRip] [Hi10] [1080p]'
21-1-4 13:11:48.4|Debug|Parser|Episode Parsed. Katanagatari - Season 01 
21-1-4 13:11:48.4|Debug|Parser|Language parsed: English
21-1-4 13:11:48.4|Debug|QualityParser|Trying to parse quality for [RH] Katanagatari S01 [BDRip] [Hi10] [1080p]
21-1-4 13:11:48.4|Debug|Parser|Quality parsed: Bluray-1080p v1
21-1-4 13:11:48.4|Debug|Parser|Release Group parsed: RH
21-1-4 13:13:18.4|Debug|Parser|Parsing string '[RH] Katanagatari S01 [BDRip] [Hi10] [1080p]'
21-1-4 13:13:18.5|Debug|Parser|Episode Parsed. Katanagatari - Season 01 
21-1-4 13:13:18.5|Debug|Parser|Language parsed: English
21-1-4 13:13:18.5|Debug|QualityParser|Trying to parse quality for [RH] Katanagatari S01 [BDRip] [Hi10] [1080p]
21-1-4 13:13:18.5|Debug|Parser|Quality parsed: Bluray-1080p v1
21-1-4 13:13:18.5|Debug|Parser|Release Group parsed: RH

Description of issue:
If torrents are added manually to the sonarr category, sonarr fails to parse season packs without a season number. For example a torrent named “[Release group] Name of show [Quality]” will fail to parse. however if a season number is manually added to the torrent such as “[Release group] Name of show S01 [Quality]” it will parse correctly. Is this the intended behavior? Because the naming without Season number is quite common for shows with only one season.

P.S if any logs or additional information is required please tell me

Not an anime user, but objectively I’d say this is intended behavior (currently), the way sonarr is coded.

I can see the benefit of allowing/parsing release names without season number if there is only one season in the show, but I guess it’s up to the devs.

Without episode ranges (common with Anime) or a season number, Sonarr is not going to be able to parse it, much less grab it. Sonarr in general does not grab full series release packs (multi-season), or unnumbered like your example here.

Grabbing it manually outside of Sonarr and then using manual import is going to be your best bet.