[Evolution] Ghost messages coming back to haunt you

["Paulo Cesar G. Costa" <paulo costafamily org>]

I have been trying to address a specific issue for a couple of months now, but
am running out of ideas. 
Basically, I have a group of 8 messages dated from 10/10/2019 that do not exist
in the mail server (my other computer and the phone email app do not see it, neither does the webmail app) 
but keep showing up in my notebook computer. 
The messages appear listed in the message window as not read, but when you
select them you get this warning instead:

> Unable to retrieve message.
> The specified object was not found in the store., The process failed to get
> the correct properties.

I then delete the messages and all seems right. However, after I close and open
Evolution again the messages (together with the warnings) come back again.
If instead of deleting I just mark the messages as read, when I restart
Evolution they will come back as unread.

I did try to refresh the associated inbox, which again works until the next
restart.
I also tried deleting ~/.cache/evolution/mail/[long number]/folders.db
which seemed to work initially, but I then got the messages back again.

Details:
* account is a corporate MS Exchange (university)
* evolution 3.34.1-2 
* Pop_OS! 19.10 / gnome

This issue is constrained to my notebook, so I assume that some point in time I
actually deleted those messages but some index in my notebook became corrupted
and kept the messages pointers. 
I would simply try to delete the whole account and reinstall it, but would
prefer to understand what is going on before trying the brute force method.


Thanks,
Paulo