The skin file is probably in the wrong place (read the post in the link below) or you are using a skin other than Default in which case you need to copy the NetflixSkin.xml from Default Wide to the folder of your chosen skin.
https://forum.team-mediaportal.com/threads/new-netflix-plugin.112963/page-2
https://forum.team-mediaportal.com/threads/new-netflix-plugin.112963/page-2