Auto Sharing not working: OAuthException: (#100) Invalid parameter

Auto sharing via Ultimate Facebook is not working for me. I receive the following error message: OAuthException: (#100) Invalid parameter.

Hopefully it is un-related to my other issue:

Any help would be great!

I have already tried activating, de-activating, uninstalling, re-installing & re-activating the Ultimate Facebook widget—no luck there.

I have also double checked my Facebook App ID and Secret, refreshed user token (just before posting a new post/event).