folder structure problem in classic outlook

Hello great people of Mailbox.org!

I'm experiencing a persistent folder hierarchy problem - since about a month - when accessing my mailbox.org account via Classic Outlook (IMAP) on Windows 11. Outlook shows several incorrect/old folders (including “temp-1” folders) that do not exist on the server. The folder structure appears correct in mailbox.org webmail, on my iPhone (iOS Mail), and in the New Outlook client, which suggests the mailbox itself is clean.

To troubleshoot, I have already:

• verified that the folder structure and subscriptions are correct in webmail,
• rebuilt Outlook profiles multiple times,
• deleted the OST cache and RoamCache,
• performed a full Outlook registry/profile reset,
• allowed a full resynchronization from the server.

Despite these steps, Classic Outlook still recreates the incorrect folders during synchronization. Anyone having the same problem? Any luck with resolving it so far?

Thank you for your help.