Thanks for the logs and DB (I thought that you will send them as a PM to me, because now all can get an access to some your private data...), luckily I'll have some time a bit later to take a look at them. Meanwhile, can you switch between thread/single message modes? Is it reproducible only in thread mode? if yes then looks like it is a backend issue (my mistake ).

P.S. is it happening after you are getting some new mails when pressing on a "get more messages" button?