LO2 is in our Ikea Antilop still. She stands up in that and asks to get down, then says 'knee, knee' and eats our dinner, and her own. At least she's eating well, right?!
I had a hunch it was to do with the chair and swopped her into the (imitation) Tripp Trapp chair, with the bar put back on for her. She didn't budge. I think she couldn't, but then she didn't ask to get down either. So it might well be a hardware problem.