dataflash compatible with ATTINY programming ?

Can a Dataflash chip be corrupted by leaving it connected the SPI pins when programming the MCU, even though the WP pin is asserted?

I am using a ATTiny841 to read a Dataflash 1Mb SPI flash storage chip. I program it via SPI on an UNO and then transfer the chip to the 841 breadboard. The Dataflash SPI pins are now connected to the same pins used to program the 841. I have found the Dataflash data gets corrupted periodically, all of the written data. I think it's due to the dataflash getting the 841 programming signals, however, I have the DF write protect pin grounded and nothing should happen as I understand. Should this work or do I have faulty hardware?