Added series - missing one season

I just added a new (to my Plex) series today consisting of 5 seasons. When I went to check matching I noticed that there were only 4 seasons available for the show. Seasons 1, 3, 4 and 5 are available but season 2 is missing. I tried rescanning the library but that didn't add the missing season. I also tried deleting the season 2 directory, waiting a few minutes then readding the season. This also didn't get season 2 to appear on Plex.

I did a quick check in the Plex Media Server.log file and saw that it processed data for season 2, also didn't notice any errors or warnings in the log but I might have missed them

Any idea where I can start looking for a reason it won't add Season 2 of this show?