The Update Limit Price feature on basket orders is working differently today than yesterday. In fact, I don't think it is working at all but my experience may be unique because I use it to update what are called limit prices on relative orders whereas most people probably use limit or market orders. I say "what are called" because I think the number you put in the limit price field is, in fact, the maximum limit price for a buy order or the minimum limit price for a sell order when you are using relative orders.