Hi, I've got a problem with the way Kmail is displaying message headers, and I'm not coming up with the right search terms to find a solution.

The message list pane is blank, with no details of subject line or sender, but the hover-over popup has all the information, and the email itself still displays normally:



I've got two accounts set up, one pop and one imap, and both are doing it. Is there a way to force Kmail to refresh the way it displays the message list?

I'm using Kmail 5.1.3 on Fedora.

Any advice is much appreciated.

Your problem is that only the «Status» column is being showed at the message list. I have the same problem but only when I open a new tab. The "original" tab shows things well, but the additional tabs only show the status too.
I think this is just a bug that should be reported to bugs.kde.org, but in the meantime I "solve" it temporally placing my pointer at the left of the word «Status», few pixels at the left, before reaching the vertical separator line, or whatever it is called, that separates the message list from the folder list, then the pointer's icon changes to indicate that it is over a zone that can be "stretched"; then I click and drag to the right, and the «Message» column is shown with all its info (subject, date, etc).
I think it's pretty similar to your problem and should work too, but temporally, because the next time you launch Kmail the problem will persist and you'll have to repeat the process, at least so it does for me, so it's not a real solution. In my case, as it only happens when I open additional tabs, doesn't bother me much since I don't use tabs in Kmail too often, but I think in your case you should better file a bug.

If you find a definite solution or file a bug at bugs.kde.org, please, comment here, I'll be pleased to support and comment it.

Had the same issue on my newly upgrade Kubuntu 16.04

Changing the default theme (Settings > Appearance > Message List > Default theme) should help.