This seems to be intermittent. I've since restarted Evolution and it appears to be functioning normally again. It looks like a variation on the hang problems I've always had and not known just what to say in a formal bug report. In that case after Evo has been running for a while it seems to stop responding to the selection of new messages. Restarting has always seemed to fix that. In the case of this new thing, I can go from message to message, but it seems finicky in changing the read or delete status.
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