Local mail folder and sub folders disappear -> MS Outlook 2016 on Big Sur

Hi all.

I recently upgraded my Outlook client, after the upgrade I was still originally able to see a local folder called MyArchive, in which I ran a folder per year, for every years emails.

All under the On My Computer root folder, this entire tree of MyArchive have simply disappeared,

how where can I look for it and get outlook to display it again.

I DEF did not delete it. The New Outlook option is also disabled at the top right of the outlook window.

G