Today's PreciseManeuver is not playing well with today's 1.1 Prerelease. The problem seems to be caused by the mod; it consistently happens when it's the only mod installed, and consistently does not happen when no mods are installed. It manifested in a fully unlocked career mode game and also a fresh sandbox game. The problem:
I set up a simple ship with a pod, tank, engine, and parachute. There are two stages. I take the ship to the launchpad. I see the staging light is blinking green. I hit M to switch to the orbital map. The staging light turns red as the GUI disappears to the left and the orbital map appears. I hit M again to switch back to the vehicle view. The staging light stays red. I am unable to unlock the staging with ALT+L. When I try to advance the staging with spacebar, nothing happens. It's permanently locked.
The behavior when I hit M a second time without the mod installed is that the GUI appears again, the light is still red, and then the light turns to flashing green again. The staging state has been properly restored, and the ship can be launched.