A blank block was mined at a height of 844689 in Bitcoin

ChainCatcher message reports that, according to mempool data, an empty block was mined at Bitcoin height 844689 (i.e., the block only contains one transaction for the block reward Coinbase), with only a 12-second interval from the previous block height.

Miners pack empty blocks out of economic considerations, making this the wisest choice for them. To make full use of this time for mining and to avoid conflicts with transactions packed in the parent block, miners cannot fill the block with transactions, meaning they can only attempt to mine empty blocks.