Plasma 5 oddity?

Doing F22 beta testing I ran into something I found rather odd. I don't care for the default Breeze theme so I was experimenting with various themes installed via the "System Settings" gui. Everything seemed to be going well. However, when I went back to Breeze the icons in the systray didn't revert to the Breeze ones. I logged out and back in and even rebooted. Still no change. I was in a bit of a rush, so I just uninstalled the themes, logged out/in, and things are back to normal. Can this be explained? -- If you can't laugh at yourself, others will gladly oblige.