Managing personal Outlook.com account settings, security, and privacy
I spent hours trying to contact Microsoft about this problem, without any success. The only way I could find to stop the blockage was to use my daughter's Microsoft 365 - it allows her to allocate slots from her account. This was 100 per cent successful. Had it not been for her account I would still be trying. It was extremely lucky I could rely on her.
The only similar way I can think of is to buy Office 2021 from Amazon (about £30), use the Control Panel to uninstall your existing (blocked) Office, ,then install and activate your new version. If that doesn't work apply for a refund from Amazon.
Alan