Don't jump into conclusion without checking other things first. Have you updated the drivers on the Apollo? Have you checked their forum if others have the same problem with spdif?
Open a support ticket then. No one else can't help you here if it's the kemper. Only the support team can.
I just wondered if anyone has the same problem as I do. Well, then I'll do that. 
I had a similar issue (maybe even the same) a few years back ... with the same cables. Here's what had happened:
These cables sat very tight on the S/PDIF sockets of the Profiler. Every once in a while they had to be disconnected, e.g. to move the Profiler somewhere else or when we did some changes in the studio.
At some point we started to experience signal drop-outs ... long story short: The S/PDIF sockets' 3 pins are just soldered on the board, there's nothing that fixes them tightly to the backplate. We figured that one solder joint had gone bad, probably due to the force we had to use to pull out the cables. We just re-soldered it properly and we were fine.
Since then we always carefully turn the jack a little while pulling it out.
I wouldn't recommend doing this DIY (if that's the case with your Profiler) but since this particular Profiler sits in the studio in Kathmandu/Nepal, sending it in for repair was no option.
I had a similar problem as lightbox For about 2 years I had to twist the plug around to make contact.
Eventually I opened my toaster up and slightly bent part of the socket to make better contact.
That was about 3 years ago...had NO problem since.
YMMV and I wouldn't do this if you are in warranty or unsure what to do.
