I had a minute tonight to look into the drive strength options. Looking over the HW manual I found DR_STR[1:0] Address 0x14[5:4]. This controls the drive strength for SCLK, AP0-AP5. The default is 10 (Medium High 3x). Interestingly enough as I increased it things got worse. Things actually got better when I decreased it. When I decreased it to the lowest level 00 (Reserved) all channels functions correctly.
I am not sure what level 00 (Reserved) is at but if it is increased just to 01 (Medium Low 2x) I start to have problems. However 00 seems to fix our issue. I am able to run all 8 channels out of the APx port without any issues.
Shawn