I have had this happen when switching between Standard & Mini views as well (Build 14.0.50 dual-screen setup).
When I launch MC14 and press Ctrl+2 for Mini View, the screen sometimes expand mini view to fill the whole screen (as experienced above). When pressing Ctrl+1 and Ctlr+2 again, it will display the mini view correctly, except that it is streched horizontally to the width of the screen.
More often, however, the MC14 mini view window disappears completely after pressing Ctrl+1, only to reappear when clicking on another window or the desktop. When this happens, the mini view has been resized to it's smallest allowed size and moved to the bottom-left corner of the first screen.
After this, all seems to work fine. This did not happen with the previous builds.