I'm having same problem on my MR16 controller.
Controller works, but can't change starting channel. I know that my Lynx DMX dongle is set right with address utility: if I put MR16 in operate mode and turn on Lynx address utility, brightness on first channel changes. Let say I want to set channel 17 and hit program brightness on 1st channel will be dim, if I set starting channel 98 and hit program, same channel 1 will be brighter, so it looks like address utility sending a code via DMX.
I've reflashed PIC, made no difference. I'm waiting on some parts from Mouser so I can build second MR16. Will try if that will work, if it will - I'll just program starting channel and swap PIC's. If it wont, will start some troubleshooting. Will keep you updated