For some reason, the graphical update notification test isn't working right for KDE. We don't get an update notification in the test, but I've tested manually with Fedora-27-20171016.n.0 and update notification does work in KDE in a manual test (just install from the live image, boot the installed system, and wait for a notification for the updates that are in updates-testing).

The test does something more complex than this to try and ensure updates will always be available, but somehow that's not working right any more. It did used to work right. We need to look into the KDE logs, probably, to see what's going on.