You missed the trading time, so you didn't participate in the trading today. Your margin account will be transferred into or out of today's profit and loss on the basis of yesterday. Since futures are settled daily, even if you don't participate in the transaction, your margin account will participate in the settlement, and the profit and loss will change.

If you don't pay attention to the change of margin account or the trend of the market for a long time, you are likely to miss the best time to close your position. Once the amount in the margin account is lower than the minimum requirement, you will be required to add margin, otherwise you will be forced to close your position.