Hey Leonard,
I made the experience that there are big differences between HDMI cables, and I mean not only whether they have ferrite cores or not. At the office, I have the monitor image of an Eizo going black for a moment when I switch devices nearby off, this happens with some HDMI cables, with others not. Others refuse to work with my KVM switch or with an HDMI audio extractor. And it’s not that you can predict that from the cable specs or so. Trial and error.