Mail: Missing email body in 'On My Mac' subfolders post Tahoe update

Hello, upgrades to macOs Tahoe yesterday and have an issue with mail. I have organised folders and put may email in themed subfolders (under On My Mac).

Since yesterday, Tahoe Mail WILL open them with all headers intact, but their body text doesn't display. I can see the message size indicator (eg: 80 kb, 2mb) but absolutely nothing in the body of the email. All subfolders have the same issue.

So I am not talking about the email accounts, where the emails initially land, but the customised local subfolders i have created, visible underneath in the mail sidebar.

When i go to library/ mail/v10, i can only see the accounts and the existing emails that have been received recently and are not yet dispatched elsewhere in the subfolders.

In library/mail there is no trace of these subfolders, and I have no idea how to find them or retrieve them from the TimeMachine on an external drive either.

I am doing a search for some of these emails in the Spotlight bar, i spot some, but they don’t open when i click on open or quick view.

I would love to find the emails and ensure the content in the email body is visible.

Can someone help please? This is distressing!

Thank you!