When trading U.S. stock options, you may sometimes observe that some orders are filled at worse prices but your own order placed at a better price is not filled. This may be caused by the following reasons.
1. The liquidity of the options market is normal. However, due to the special quotation rules of the U.S. market (BBO / NBBO), the bid and ask you see are the highest bid and lowest offer price of a particular exchange. Some orders may be routed to other exchanges for transactions.
In addition, when the market is inactive, it is possible for quotes from different exchanges to vary widely but not be updated timely, which may result in orders not being filled.
2. Since there are Spread Orders in the market, an individual buy/sell order may not be filled.
For example, some brokerage firms allow customers to make a spread order by placing a long call order and a short call order. Both orders will be filled at the same time only if the prices of both orders match the ask and bid.
To take a specific example, an option on BABA has a bid price of $3.00 and the order is part of a spread order matched on the exchange. Submitting a $2.80 sell order at this time will fail to fill.
All of the above descriptions are normal for the U.S. market. The options orders have been submitted and the outcome depends on the exchange.