I can't seem to find any solution to this problem but getting 4K video from the GH4 using the H920 / SB24 seems impossible. Anyone found a workaround for this?
Apologies for the delay in replying. This issue has been identified by Yuneec but they blame Panasonic and say it's a software issue with the GH4 communicating with the ST24 controller. Effectively the HDMI wi-fi link fails when you choose the 4K option in camera. The GH4 will of course shoot 4k but you can't monitor the image in-flight and that's a significant problem which customers who bought the earlier model H920 were not told about.