Office Home & Business 2019 license no longer recognized after reinstall ("No license found")

Hello,

I am experiencing a very similar issue with a genuine Office Home & Student 2019 for Mac license.
My license is still listed in my Microsoft account under Services & Subscriptions and was added on March 30, 2022.

What makes me think this is not a local Mac issue is that Office stopped activating on my previous Mac a few months ago, before I replaced it. I recently bought a new MacBook Air M4 and the exact same problem persists.

My configuration:

- MacBook Air M4
- macOS Tahoe
- Office 16.78 (installed using the Microsoft-provided installer)
- Office Home & Student 2019 perpetual license

What I have already tried:

- Reinstalling Office completely
- Installing version 16.78 specifically recommended by Microsoft
- Running the official Microsoft License Removal Tool
- Removing Office containers and activation data
- Restarting the Mac
- Signing in with the Microsoft account that owns the license

The activation process starts normally. I enter my Microsoft email address, but before it even asks for my password, Office immediately shows: Unknown error. Error code: 0x0

The license is still visible in my account and Microsoft still offers the Install button.

Has anyone else seen error 0x0 during activation of Office 2019 for Mac recently?

At this point, I'm wondering whether this may be related to Microsoft's activation services for older perpetual Office 2019 licenses rather than a problem on the Mac itself.

Thank you.