Reason 1: The trader has placed a sell order. However, the price of cryptocurrency has fallen so quickly that the sell order did not find a buyer to complete the sell. The trader will continue to wait for the settlement of the total sale. Usually the exchange has already sold part of your order since they have the right to sell your order in pieces to fulfill supply and demand. Should the price rise again and reach the level of the sell order, the remainder of the order will be processed and sold. If you don't want to wait for that, you can press the red cross and have the sell order processed.
In this case the trader cuts your order into 2 pieces; the sold part, which appears in your sales transactions on the one hand, and the unsold part which appears in purchase transactions. Both orders have the same order number. The fact that the order has not (completely) been sold is because the trader places a market order. This means that it gives a fixed price at which to sell. The exchange may not deviate from this market order. In the case of coins that are not widely traded, this situation of partial sales can arise if the price falls.
Reason 2: The trader has placed a buy order, which cannot be completely filled in by the exchange due to the rapid rise of the price. As long as the trader is waiting for the order to be processed, there is a red cross in the order line. Only when the price starts to fall again will the exchange complete the rest of the transaction. Also you can instruct the trader to deal with this by pressing the red cross. Again, the transaction is split into two transactions: the already purchased portion appears in the purchase transactions screen, and the remainder appears as a 'zero order' on the sales screen.