Do not attempt to use an NCE 5 amp / 10 amp / Power Pro / PH-Pro / CS02 system to program CVs>256 in program track mode using the Pro Cab. You will corrupt other CVs in the decoder.
Your options are:
1) Use the built in serial interface and a PC running JMRI / DecoderPro. It knows how to work around the firmware bug in the Power Pro and it also takes care of setting the index CVs 31 & 32.
2) Use Program on Main but you MUST first manually set the correct values in both CVs 31 & 32 BEFORE changing any CV>256.
Thanks to NCE "Super User" Dave Heap for this information.