unread messages noy showing

Where are they shown as unread messages for you to read?

The images shown above are of the exact same folder. On the left we have a number of sub folders showing. In the one on the right is a collapsed view of those folders, but the unread unread count is added to the parent folder and it is shown in the list as a coloured outline and coloured text. On the full view that button is the coloured thing, not the text.

Is the folder containing the unread emails perhaps collapsed?

Same here. As of maybe a week ago, my Tiscali (TalkTalk) account shows there are unread messages on the left but doesn't show them in the list of emails. I have tried Rebuilding the folder and that works, but then #i have to do that every time.

I use unthreaded conversations, so just a list of emails in the order I received them. I try changing the listing criteria but that makes no difference.