Stuck on “WOOF settings saving ..”

The plugin seems to be having some sort of error on any attempt I make to save (even if I don’t make any changes) and the message “WOOF settings saving ..” is just stuck on the screen.
Any idea how to resolve this? I’ve had a previous version of this plugin installed in the past, perhaps the setting format has changed? If so which table do I need to delete to clear the plugin settings?