DRV8889-Q1: SPI question

Dear team,

When we first write OP_CTRL_1=01100110, SDI=00001000 01100110, then we found that the lower 8bit of SDO is 00000000 instead of 01100110. After 10ms, we write OP_CTRL_1=01100110, SDI=00001000 01100110 again, then the lower 8bit of SDO is 01100110. Could you please help analyze the reason? Why first write is failed?

Is it related to below description? But I don't understand below description clearly. Could you please help clarify this?

Thanks & Best Regards,

Sherry