No Results for /sites?search=test

Hello,

first of all I whish you a Happy New Year!

I want to search in my sharepoint sites for specific names and moreover I want to get a list of all sharpoint sites. Therefore I am using the following URL in the Graph Explorer:

https://graph.microsoft.com/v1.0/sites?search=test

or

https://graph.microsoft.com/v1.0/sites?search=*

Now it becomes strange:

When using an account from Company A everything works correctly. I receive a nice list of all results.

But when i am using an account from Company B, I only get the following 404 NOT FOUND response for all queries (although there should be multiple results):

{
    "error": {
        "code": "itemNotFound",
        "message": "Item not found",
        "innerError": {
            "date": "2022-01-01T14:59:35",
            "request-id": "xxxxxx",
            "client-request-id": "xxxxxx"
        }
    }
}

It would be great, if someone has an idea of how to solve the problem.

Thanks,

Claudio