Can't access MS bookings URL: This information can't be retrieved right now. Please try again later

Hi all, 

On a client's tenant, I have a user who cannot use Microsoft Bookings. This user was previously converted to a shared mailbox and later switched back to a user mailbox. Currently, a Business Premium license is assigned, and Microsoft Bookings is enabled under the assigned apps. I have already disabled it, waited a day, and re-enabled it, but the issue persists.

Whenever the user accesses the link https://outlook.office.com/bookings/, they receive the following message: "This information can't be retrieved right now. Please try again later."

The problem is not related to caching; I have tested this in all browsers, incognito mode, and on different computers. The issue is isolated to this account. All other users with the exact same settings can access Microsoft Bookings without any problems.