I had Fox Sports Go working fine up until a few days ago. When I went to watch the channel, it gave me the "activate" message window with an activation code. I went to the website and logged in with my provider, I then used the code to activate the channel. The activation window on the TV did not go away, although I am able to watch content on my computer from Fox Sports Go. No other apps have been affected. I have removed and reinstalled the app and power cycled the roku. The roku is up to date on the latest update.
Why will the channel not activate on my roku device?
For more information about that channel's authentication and functionality, you'll want to contact the channel provider support directly to inquire further. Many channels on Roku are developed and maintained by the channel provider themselves.