The GH4 is actually pretty good at focusing now, especially with the Panasonic lenses.
Depends what settings you are currently using.
It has a focus feature called DFD "Depth from focus" (and not phase or contrast detect like other cameras) that does not "hunt" for focus but tries to gather the information from the amount of bokeh in the picure.
Not sure how well it handles the Olympus lens which you are probably using, or what settings you use, but if taking stills only I would put the F stop wide open minus 1 or 2 stops if you can, and try and focus on something that has a lot of detail in it (not a wall which is all the same colour).
The focus on the GH4 is really very quick so you probably won't even see it with a 12mm lens when you are set to AFS/AFF. (Auto Focus Single)
Go into your menu and see what it is set to, AFF is like a hybrid of AFC (auto focus continuous) and it will try and re-focus if you have recomposed and will give you different results.
Its best if users are having problems that they let us know what they are currently using.
Again I do not have this lens so I am not sure how it focuses automatically with the gh4.