Artwork not downloading

[prsinister]

Sonarr version (exact version): 2.0.0.4201
Mono version (if Sonarr is not running on Windows):
OS: Windows 7 64-Bit
((Debug logs)) (posted to hastebin or similar):
Description of issue:

The last 4 Series i added, none of the artwork was downloaded.

Athena: Goddess of War
Animal Kingdom
Geordie Shore: Big Birthday Battle
Wrecked (2016)

The poster is visible in Sonarr but the files are not in the Series folder. All metadata for Kodi is enabled in Sonarr.

Unfortunately, i had cleared my logs before i noticed it so all i have been able to find is an EventAggregator Error:

MetadataService failed while processing [MediaCoversUpdatedEvent]: value [fanart.jpg] is not a valid Windows path. paths must be a full path eg. C:\Windows
Parameter name: path

[prsinister]

Ok so when adding a new show, it doesn’t download the artwork. But when going to the show and refreshing, it then downloads the artwork.

[markus101]

Looks like its related to:

Error: "ExistingMetadataService failed while processing "

so that error disaapeared, but I have the old error back: Message: MetadataService failed while processing [MediaCoversUpdatedEvent]: Object reference not set to an instance of an object Exception: System.NullReferenceException: Object reference not set to an instance of an object. at NzbDrone.Core.Metadata.Consumers.Roksbox.RoksboxMetadata.EpisodeMetadata(Series series, EpisodeFile episodeFile) in M:\BuildAgent\work\6c3239faf2b92630\src\NzbDrone.Core\Metadata\Consumers\Roksbox\RoksboxMetad…