1. !!! After a hardware reset of PPI 8255, you MUST wait a while that internal PPI reset procedure finishes, otherwise PPI initialization will not be done properly. (100 ms is a good choice). So after the system reset, call a delay of 100ms and then initialize the PPI with a control string to set the PPI mode.
(I have lost lot's of hours finding out, why the system was not working. The reset startup delay is also different for different PPI manufacturers, but from my experience 100 ms is enough.)

2. Check your address decoding logic where your 4 PPI registers are located. Could be that you are writing to the wrong locations.

Franc