I hope this isn't out of line because I can understand how frustrating it would be but she could genuinely be shy. Reading through your post I just related so strongly to the experiences.
Me too. Sometimes its hard for others to realise how hard it is when you are shy.

I think you could talk to her about it, but not if others are around and try not too be confrontational. Maybe try to get her to open up when its just you, your DSS and her.