I use SPDIF all the time for tracking and reamping. It's part of my workflow, especially when I record pedal steel - I have templates set up in Pro Tools to record the steel via DI (SPDIF), Stack (SPDIF), and time based effects (DLY/REV Wet via main XLR outs). I also reamp via SPDIF if I do any editing on the DI track.
I recently upgraded to the latest Kemper OS, and I started having a weird issue. I always set the KPA as my SPDIF master clock source - since it was made before 2018, it can't function as a SPDIF clock slave. ***EDIT-This turned out to be an incorrect assumption - see below - my KPA was made in 2018***
No problem, I'm already accustomed to changing the clock source on my interface (Apollo 8 ) whenever I use the Kemper. But, after the OS update, the Apollo would lose clock sync randomly. The clock source would flash red on the Console app, and the audio would mute as it searched for the clock. After the audio came back, suddenly my session was playing back at the wrong pitch, about a quarter tone sharp! Being that I play an instrument without frets, I immediately thought it was my fault and tried to correct - but I'm like, wait. Something's up.
After spending about 2 hours troubleshooting, using contact cleaner on my SPDIF cables, ordering new SPDIF cables (I didn't cancel the order, always good to have spares), I figured out what happened. In the Output menu on page 6/8, there's a checkbox where you can select Auto or Internal for the sample rate. Auto makes sense if you have a post-2018 Kemper that can slave to an external clock source - it just does it for you, no effort required. But if your Kemper is older, definitely switch that back to Internal, and continue setting the Kemper as your master clock source! I guess the new OS had Auto selected by default.
Update: see below - if the Auto option appears, the KPA can function as clock master OR slave.