I have a similar story:
The connection between my profiler and Rig Manager on both a Win 10 computer and a Win 7 audio computer built by Sweetwater just stopped one day over two years ago when it was still under warranty. I reinstalled all the updates available at the time on both the profiler and RM. I tried new USB chords but nothing fixed the problem. I got frustrated with it and put it away for a few months. When I started back with it, I finally called Kemper support after going through the same steps as before. The tech said it probably was a windows 10 from win 7 upgrade that caused my computer to stop communicating with Rig Manager. He said if I couldn't get it to working, I could send it in and they would fix it.
I won't go into what a procrastinator I am, but here we are, 10/18/20. The Kemper Profiler still works like a jewell. Great sounds with the rigs that come in it. It just can't communicate with Rig Manager. The Toast ME editor works fine with the midi to USB adapter by the way.
Now that I'm determined to get this resolved, I've been researching for the last few days and found a reference to this problem on a Kemper-Cakewalk forum. One poster mentioned that Rig Manager should show up in "Sound, video and game controllers" in Device Manager. It's not there on either of the two computers I've used with the Kemper. I'm pretty sure they used to be there when it was working. I have gone through many of the steps you listed, installing the two newest updates for the profiler and DM. I was just about to start trying to manually install drivers on the Win 10 but I can see from your experience that that probably isn't going to help.
Worse case, it could be an issue with the Profiler USB type B port on the back of the profiler. I'm probably about to send mine off to British Audio in Nashville, Tenn. Yesterday, a tech there told me that they have replaced the entire circuit board that includes the USB port, but he had never heard of an actual problem with the USB port. They have replaced circuit boards under warranty for other issues and that Kemper just sends them the entire circuit board. It's got to be pretty rare for a USB port to just fail, unless we're putting great stress on the chord or being rough with it. I don't know about you, but mine was on a table and was clear of obstructions and hadn't moved for over a year when it just stopped communicating.
It could also be a software issue that only a handful of people have had. I've spoken to people at Sweetwater and at Kemper and none of them had heard of this problem. I would love to get mine fixed without having to send it off considering it's now out of warranty. That's my fault. But, as a plus, since Sweetwater pointed me to British Audio ( an official warranty repair center for Kemper), it turns out they have a couple of pretty neat upgrades for Kemper Profilers, so if I have to send it to them, I'm going to get the power amp upgrade.
Good luck with getting your problem resolved. Kempers' are great by themselves but they're so much better when you have access to Rig Manager and are easier to update.