While we are waiting for the real fix, this workaround may (or may not) be enough to get GH5 going, assuming you are currently at the latest version (2.6, 2016-12-16). There is a jog lever on most Speed Boosters. Press it inward and hold it down, and while keeping it depressed, either power on the camera (if the SB and lens has already been attached), or attach the SB or the lens (if the camera is already powered on). Do not let go until the camera has fully started up, which may take a sec