Ultimate Facebook stopped working...looks like a few months ago in the log.
Getting "Invalid OAuth access token signature." and "Invalid appsecret_proof provided in the API argument"
Setup a new key, searched help and watched the video here: https://www.youtube.com/watch?v=q3-XfRjXFIk&feature=youtu.be
Deactivated all plugins except WPMU Dashboard and Facebook
Still getting error "Please, enter correct Facebook API settings and make sure Facebook app is public