You may only be attempting to write back to the EE device too soon. The have a cycle time around 5ms to 20ms in which the device is non-responsive as it goes through its internal state machine to write the information yo clocked into its shift register buffer, into its EEProm memory.

Your code should be able to detect this non-response mode by its failure to acknowledge, but its sometimes overlooked by people writing drivers.

If this is your problem, changing the code around wouldn't appear to change things.

Beyond that, we'd need more information aobut what other functions you have tied to the same signals going to the EEProm and whether any of those chips are being serviced by interrupts.

Also, be mindful of how you "park" your data and clock lines to the device.

aka J