I've been working with the Network Manager without any modifications and for some reason, in the current project I'm working on, it won't accept any scenes I try and drag into the Offline Scene and Online Scene slots. When I go to add them nothing happens and it just stays with "None (Object)". There is no feedback given in the Editor / Console (tracked here: http://issuetracker.unity3d.com/issues/no-feedback-when-unable-to-add-a-scene-to-networkmanager) so I have no idea why it...
Can't add scenes to Network Manager slots in inspector
Can't add scenes to Network Manager slots in inspector