Sometimes when I open an application, the program will open, but it won't display in the launcher or in the Alt+Tab dialog. Here's a screenshot of VLC open:
As you can see, the icon doesn't appear in the launcher even though it's clearly open.
I'm also not able to drag the VLC icon from the dash into the launcher, like I can with other programs.
Right now I can only get it to work with VLC, but the other day it also happened to Transmission. Note that some other applications (e.g., Terminal, Chromium, etc.) are all fine.
Also, it's not always this way. VLC was working just fine yesterday, for example, but then this morning it stopped.
It's really frustrating because I have no way of accessing that window other than minimizing everything else to make sure nothing covers it up.