Same problem here. I use wordpress 3.3.2, and Simple Fields 0.5
The document said that
Different post types can use different field groups – actually you can even use different field groups even for same post type
But I cannot use different field groups in one post. When I change the connector, my previous connector’s simple fields value was cleared up.
I was very excited to use this plugin till realise this problem.
This is a big bug. Please fix this.