I too have been dealing with this issue on my kemper as well. I've seen it with previous OS versions in addition to the current version I have loaded on the kemper rack (126.96.36.19997). Does only appear to occur when the remote is connected. I am using reaper to automate live shows and have it controlling the kemper. It looks like reaper does midi CC chasing on play where it sends out the last state of all the previously modified CC's. So as the setlist progresses, I have modified more and more CC's and the probability that the kemper will lock up increases. Here's a sample of one blast of midi CC data that has a high probability of causing the Kemper to hang:
0: B0 11 00 [CC17 GP Slider 2 MSB] chan 1 val 0
1: B0 14 00 [CC20 MSB] chan 1 val 0
2: B0 16 7F [CC22 MSB] chan 1 val 127
3: B0 32 00 [CC50 GP Slider 3 LSB] chan 1 val 0
4: B0 33 00 [CC51 GP Slider 4 LSB] chan 1 val 0
5: B0 34 7F [CC52 LSB] chan 1 val 127
6: B0 35 7F [CC53 LSB] chan 1 val 127
7: B0 36 7E [CC54 LSB] chan 1 val 126
8: B1 32 01 [CC50 GP Slider 3 LSB] chan 2 val 1
9: B1 34 01 [CC52 LSB] chan 2 val 1
10: B1 35 01 [CC53 LSB] chan 2 val 1
One other thing to note (something I just noticed as I'm typing this)....Even though in my example here, reaper is sending out channels 1 and 2, I have a remapper on this data which remaps all channels to 2 so those chan 1 messages are going out the HW to the kemper as channel 2 (kemper is setup to rx on channel 2)...So not sure if the kemper doesn't like the fact that it's being blasted with all these commands at once, or the fact that there's a command for CC's 50, 52, and 53 immediately followed by another value for those commands, or a combination of both.
EDIT: another thought that occurred to me after reading through the manual again, since in performance mode the CC50-54 are simulating the button presses on the remote, and the way I am interpreting the manual is values 1-127 is button press, value 0 is button release....is the kemper not liking the fact that it's seeing 2 button presses but no button release for 50, 52, and 53.