I know of one person that does this during meetings. He's a great guy, so I didn't want to say anything, but during some meetings, I noticed that he is actually facing his body away from the table as though he is completely disengaged and couldn't care. It bothered me a lot -- and now I know (I think) that he actually is high energy, so his legs (one or both) are often tapping staccato. Is he ADHD? No idea, but with his legs under the table, he would easily run afoul of the table legs with his moving feet. What I want to say is her body language could be nothing more than a physical issue or something unrelated that is going on somewhere else in her life. I would be interested in your thoughts on this.
The other thing that this COULD be -- is she very shy OR is she perhaps holding back her own opinions or ideas? I wonder if this would lead to mixed messages like this. Perhaps draw out her opinion or ideas and see if her body language changes. (I would be interested to know if this helps.)
As you can see -- all only my opinion.