Are you trying to buy at the bid? Or did you send in a limit order to buy at a mid-point and the bid became your order? I agree the liquidity is not there yet for splitting the bid/ask perhaps, but I placed a large order at the ask to buy and it was filled immediately (i.e. no partial fill BS and move the ask higher).

so I do not think a move from 11.75 to 12.75 will give us any real indication of how the calls will move when VIX triples in a day or so.