I was attempting to do this same thing and I spent a couple days researching this to no success. I eventually came to the conclusion that many of the articles, such as the one linked in the original post, are only relevant if the RAID is created using Intel RST raid controller. The method described in all those articles simply DO NOT work using AMD’s RAID controller. I have a Gigabyte AB350 motherboard.
I thought I could do an in place Windows 10 upgrade, because I was trying not to reinstall all my applications and reconfigure all the settings. I figured I could switch from RAID to AHCI so Windows could load the AHCI drivers when it was initializing, but that didn’t work either. After the system rebooted, I switched RAID to AHCI, saved and restarted the system wouldn’t boot .
So eventually I gave up. After switching to AHCI in the BIOS I did a clean Windows install on the new NVME SSD I installed, and then used Laplink PC mover to transfer my user profiles, applications and settings, files, etc. That worked very well for me.
I created an account just to reply to this post because I wished someone had done so. It would have saved me days of research and hours of trial and error, only to realize all the articles on the Internet about this topic DO NOT apply to AMD RAID controllers. Booting into safe mode after changing RAID to AHCI in the BIOS DOES NOT work. Don’t waste your time! Hopefully someone sees this post and I could save them wasting a few hours of their life.