This happens sometimes on Facebook channels!
Basically this message means that the connection between GAIN and Facebook for that channel needs re-authentication. Usually this happens when the user who originally connected the channel to GAIN has changed their password on Facebook or if they’re no longer administrators of that page.
When you click on that icon, GAIN will try to reconnect the channel by asking Facebook for permission, like when you connect a Facebook channel for the first time.
However, for this to work you have to be the administrator of the page on Facebook, so if you’re not you’ll have to get in touch with the person who is.
To fix this you have to go to Brand Settings > Manage Channel> Choose the channel that requires your attention > Reauthorize channel.