No problem. I would say that getting a scope probe of the four signals, during a looped read of the PROD_ID register would be the next step for this. Based on your configuration, I would be concerned about the signal integrity but the scope shots will also help verify the correct sequencing, coding, phasing and polarity as well. Is that something you can support? If you can post a picture of the signals, I will be glad to take a look.
Best,
NevadaMark