Fences - roll-up fences not rolling up properly

I have created several rolled-up fences that sit against my task bar on the bottom of my screen.

Many times when i go to my desktop, the rolled up fences' title bars are not snapped against the task bar; instead, they are floating up where they normally would be after the rolled-up fence is expanded, causing them to be "lost" among other fence windows that I have defined on my desktop.  To fix this, I have to expand the rolled up fence, move the expanded window away and back so that it is sitting against the task bar, and then when I navigate away it rolls up correctly again with the title being against the task bar.  I am not sure what causes this to occur or reoccur, but inevitably I will run into it, usually at least once every so often or every time I begin using my computer.  It is frustrating to deal with during my daily work and a fix would be most welcome.