Panasonic issued a new firmware update for the GH4 and G80 (or G85 or G81). You can download it here: av.jpn.support.panasonic.com
The G80 update (version 1.1) fixes that bug:
Improved image stabilizer performance during the motion picture recording.
The GH4 update (version 2.6) fixes those bugs:
– When the camera is used with the Battery Grip, an error message pops up if the remaining power of the battery in the Battery Grip is low.– With a use of Panasonic H-RS100400(LEICA DG VARIO-ELMAR 100-400mm / F4.0-6.3 ASPH. / POWER O.I.S.) or some Olympus interchangeable lenses, the monitor blacks out when the user tries consecutive shooting in manual mode in AFC setting.