I use a Mio4 to connect the Kronos, Rev2, Stage 2, and Integra. At the time there was also a USB cable from the Mio to my PC.
Yesterday when I discovered something was off with some of my combis, I traced back my steps. I did the SPLIT|STACK procedure again and saw it change my combis. At first I thought it was random changes, but after spending time correcting a few of the combis, I noticed only the timbres on channels 2 and 3 were affected. They were set to various EXi INIT programs, User BB 009 being the most common one. I run my Rev2 exclusively in Split mode, with ch2 dedicated to bass synth and ch3 for my analog poly needs.
I figured I better capture some MIDI output via MIDI-OX so I can have data to report to Sequential support. But it seems I cannot reproduce the issue. Rev2 has parameter send off, multimode on, program change receive only, and SYSEX cable assigned to USB. Perhaps the issue had something to do with the Mio4, or maybe a MIDI loop somewhere.
Either way, I'm glad I had a backup. I don't want to spend too much time trying to reproduce the issue, as I still have to fix all the other combis yet to get ready for next week's show. Lesson learned is to backup backup backup backup. Kronos has hardly any space limitations, so why not?