KDE Plasma: 5.5.4
OS: Fedora 23 x64

Issue: I noticed I had four notifications. When I clicked, I saw four progress bars (the same kind you get with file transfers) but no text. (In other words, no indication of what was happening other than a progress bar.) I hit cancel on all four and they disappeared.

Question: Is this something I should be concerned about? Is this a known issue?

Side note: thanks for an amazing piece of software! I use KDE on all my computers.