Hi Marc,
Thank you for your update.
If you have tried the mentioned suggestions and it did not work, you may kindly consider to create a new windows profile as a further try Create a local user or administrator account in Windows - Microsoft Support
Create a local user account
- Select Start > Settings > Accounts and then select Family & other users. (In some versions of Windows you'll see Other users.)
- Next to Add other user, select Add account.
- Select I don't have this person's sign-in information, and on the next page, select Add a user without a Microsoft account.
- Enter a user name, password, or password hint—or choose security questions—and then select Next.Open Settings and create another account
Change a local user account to an administrator account
- Select Start > Settings > Accounts .
- Under Family & other users, select the account owner name (you should see "Local account" below the name), then select Change account type.
**Note:**If you choose an account that shows an email address or doesn't say "Local account", then you're giving administrator permissions to a Microsoft account, not a local account.
- Under Account type, select Administrator, and then select OK.
- Sign in with the new administrator account.
And if this try still does not work, you are advise to contact Microsoft Technical support by opening a service ticket from Microsoft 365 admin center, here are the steps for your reference: Get support - Microsoft 365 admin | Microsoft Learn
- Go to the admin center at https://admin.microsoft.com. If you get a message that says you don't have permission to access this page or perform this action, you aren't an admin. For more information, see Who has admin permissions in my business?.
- On the bottom right side of the page, select Help & support.
- Type a question or keyword into the text box. If you get a drop-down list, select the one closest to your question, or continue typing your question, then press Enter.
- If the results don't help, at the bottom, select Contact Support.
- Enter a description of your issue, confirm your contact number and email address, select your preferred contact method, and then select Contact me. The expected wait time is indicated in the Contact support pane.
Thank you for your time and we hope this is helpful,
Regards,
Microsoft Community