Wow, Lots of erroneous information in this chain!
I am experiencing the same issue. In my case, I was running Windows 11 Pro (with a Microsoft Store bought digital license (it IS a license)) as a Guest on my Linux system. I had to reinstall Windows and wanted to leverage the same digital license that I had. Went to activate it through the process documented here and was unable to. Contacted Microsoft through error case and entered a phone number for them to call me back which they did (there IS a way to contact Microsoft). They spent several hours trying various things with no success and eventually said this was an issue on their side. No ETA for a fix, they just said they would email me when there is a fix. They said that I would continue to be able to run Windows 11 in the meanwhile.
I figure I will give them a couple of weeks and contact them back if still a problem.
By the way, I was told to go to "help.microsoft.com" and type "Activate Windows" as my problem. Then follow the chain to get to a person.