I've shot my first interview with the GH4 and the Sennheiser EW100 G3 wireless set plugged directly into the camera.
There seems to be a sync issue with the GH4 (and FCP X). It is slight but there. I looked it up on the internet and read a few articles about the GH4 audio being 2 frames out of sync when handled in certain editing software...

Is this a well-known issue?

How do others deal with this?

This is a serious flaw if you want to use this camera professionally...

Which type of video file are you making in the camera? Does this have an effect on the audio sync?

UHD files. Haven't tried to see whether there's a difference with 1080P... I'll try and see.

It seems there's audio issues across different platforms though and that it's not just FCP X. And it's always 2 frames. I corrected for 2 frames and it was fine.

It's strange that there seems to be an issue but it's not all over the internet. Some big bloggers like Dave Dugdale have written about it but that was a while ago. Don't know if it's solved or just forgotten... I'll write him to see if it's still an issue with his GH4...

There is a new firmware 2.0 that was released October 1, 2014 that may provide some help. Although, after reading through the new features the two-frame issue wasn't listed.

If the news was "blessed" by the marketing department (would they have their finger in the wording?) then perhaps they want to mention the positive aspects and not bring up anything negative?