Sometimes, if you've been logged out due to security reasons, it can take a while for Facebook to refresh and allow you to log in through a third party service again.
To speed up this process, you can try clearing your browser cache and starting again
Here are the steps to follow for Google Chrome
If this doesn't work, try logging into Iconosquare in an incognito session, like Google Chrome Incognito Mode.
Feel free to contact us if you are still having issues!