[Evolution] Search folders not updating

[Graham Murray <GMurray webwayone co uk>]

I am using evolution 3.4.4 with the ews backend.

In order to expire old mailing list posts, I have a number of search
folders set with conditions (Date Sent is before ....) applied to
folders to which mailing list posts are filtered. The intention is to
periodically delete all messages in these search folders. 

Each folder was populated with the appropriate 'old' messages when I
created it, but no new messages have been added to the search folders
since. I have tried right clicking and pressing 'refresh', I have
restarted evolution, all with no effect.