Sonarr creating series folder with no/wrong permissions

Sonarr version: 4.0.9.2244
Mono version: n/a (synology)
OS: DSM 7.2.1-69057.Update 5
Debug logs: 0bin - encrypted pastebin

Description of issue:
Sonarr is creating series folders with the wrong permissions. The owner is ‘sc-sonarr’ and the group is ‘synocommunity’, but permissions are set as ‘0000’. This in turn means that Sonarr is not able to create season folders or to import files into the folder it just created.

The media management settings I can see are the same for Sonarr and Radarr, with the latter not having any issues in creating movie folders and importing into them.

As soon as I manually change the permissions of the series folder, Sodarr can access them and import files.