The real 5.6d works with Radeon Software 21.5.2 and earlier, but does NOT work with 21.6.1(which Windows Update keeps forcing down my throat with every check for updates). Yes, I can go to the unoptimized kernel route, but I'd rather not have to do that when there SHOULD be a new version to support the new drivers.
Disable Windows driver update. Never used the Windows Driver update as I install the drivers I want and not
Windows.
I have it disabled, but Windows Update kept pushing updated display drivers anyway. Problem may be caused by Windows Insider build issues. I've updated to 21.6.1 and just accepted telling Phoenix to use the -clKernel 0 to get around the issue for now.