If you have the same issue on both Mac and Windows then you probably should be looking at your connections.
You mentioned trying 2 cables. But if it's through a hub, try bypassing the hub. If you're trying through a USB-C with an adapter of some sort, try a USB-B port. Beyond that, support is still the answer. Maybe something is defective in the Kemper USB port.
My issue on Windows 11 is different than the Mac.
On Windows Rig Manager opens, I can click around for 5 seconds and then BLAM! Freeze, unresponsive. Tried everything including working with their support. I mean everything.. kemper unplugged, unplugging any usb hubs and trying (per their suggestion). In other words, I can't even get it to open and be functional, with NOTHING connected.
That's why I grabbed my MacBook.. and now I've hit this roadblock.. ugggh